Erudite

In BR, the voices you hear on screen are recorded ON-SITE for these following people:
Li Yitong (Wan Mei), Qu Chuxiao (Chang An), Su Xiaoding (Emperor), Zhao Leiqi (Eunuch) and Gao Xin (Doctor)
Out of the five only LYT didn't have any theatre training - Su and Zhao, in particular are professional stage actors.
So you do hear their on-site voices in the drama (with a small percentage of dialogues re-dub by themselves in studio for better effect).
However, most of the other actors in BR has their voices replaced by professional dubbers like in most period C-dramas.
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With Ever Night, probably the sheer number of characters and dialogs involved made it difficult for them to achieve consistent thru dubbing, since it require a great deal of skill and timing - even if the persons they are dubbing are themselves (getting the exact feel of the 'moment') - so their on-site recorded dialogue were used for those scenes.

Also, Jin Han is friends with Tiffany Tang, Luo Jin's wife - from the time when the three of them work together in Princess Wei Young.

You are in luck, it will be on Astro tonight ;)
It broke new records in securing more overseas coverage than any other Chinese TV series (240 nations + streaming platforms)
http://www.china.org.cn/arts/2019-11/15/content_75411981.htm

That scene is also a visual illustration of the Chinese title: ‘Cranes Cries Over Huating (Pavilion)’ :)

There is also foreshadowing and the crane is a metaphor for the Crown Prince. Lu Wen Xi’s comments observing the crane are also quite apt.

You probably heard of the Chinese KungFu technique ‘Tiger and Crane Fist’?
Here’s a video of a real crane facing three live tigers and won: https://www.youtube.com/watch?v=lKtcl1Mo5nU

Situation is a bit more complex than that. Read first my response to @PeachBlossomGoddess below.

Even in Hollywood, very few movies are made with dialogues 100% recorded on-site. But due to expertise, budget and hard-work of their sound departments, the audience can’t always tell when a particular line of dialogue or even some words in the midst have been replaced by dubbing that is lip-sync perfectly in a Hollywood movie scene.

Like Ever Night, Royal Nirvana decided right from the start that the dialogues performed by the actors’ own voices must sound good. The producers would then proceed to plan and allocated resources accordingly to balance what is achievable by their technical crew during recording on-site and what techniques to use when ‘fixing-up’ dialogues during re-recording. Unless they revealed it, we have no way of knowing precisely what proportion of the dialogues in Royal Nirvana are recorded on-site versus being redub - because they would sound consistently good, which is the point.

OTOH, there’s some unusual cases like ‘Bloody Romance’ where the producer made all the preps for on-site recording, but in the end decided that only 4 or 5 of the cast member’s on-site voice performance are acceptable and proceed to redub all the rest using different voice actors.

A fairly common misconception is that when a drama/movie featured on-site recording, none of dialogs will be re-recorded/redub.

Take ‘Longest Day in Changan’ you mentioned - if observed carefully, you’ll notice there are places where names spoken by characters are changed during re-recording (they just dub over the spoken name).

In fact, even for current Hollywood and UK dramas, on average about 10% of on-site dialogs need to be re-recorded/redub by the actors. The difference is that the expertise in the West is so good that audience frequently can’t tell apart (that’s why they give out Oscars to ADR editors and re-recording mixers).
Here’s some interesting comparisons:

1. For the Oscar nominated (Best Sound) Sci-fi movie Contact starring Jodie Foster, 40% of the dialogues were re-recorded after filming.
Source: Randy Thom ( https://www.imdb.com/name/nm0858378 )

2. For ‘Shakespeare in Love’ the Oscar winning movie with a cast of thespians, only 2% of dialogues were re-recorded.
Source: Robin O'Donoghue ( https://www.imdb.com/name/nm0640877 )

3. In the 36 episodes Chinese drama ‘Bloody Romance’ featuring Li Yitong with in-site recording (for LYT - her first time) - only about 4% of her dialogues were later re-recorded (redub by herself).
Source: Li Yi Tong (live webcast, answering to fans’ questions)

All the leads and important supporting actors must use their own voices in this drama - the producers insisted on that for their cast, anyone not meeting this benchmark is not considered for a role.

Human, it is serviceable, and got the gist of meaning for you to follow the story but the translation wasn't accurate at times. It is possible that better versions of English subtitles will be available at later dates at different platforms.

Probably just you ;)
Anyway, if you are referring to her scene at the pavilion in episode 1, here's a little trivia, this was shot in mid April 2019, after primary filming for Royal Nirvana was completed several months back. This is to reflect that while it was winter in the Palace, the climate is different in the region of Shu (Sichuan) where Lu Wen Xi was at that time. I believe that scene actually was the last location shot with a lead that was filmed for Royal Nirvana.

Trivia:
Li Yitong and Gina Jin, who played the lead characters are born exactly one day apart in the same city (Jinan in Shandong province).
Coincidentally, both actresses also graduated from Beijing Dance Academy where they major in Chinese folk dancing.

Yes, thanks for spotting that out.
I had swapped them by mistake mentally :)
Indeed it was H&R Century that produced the TV series and later had a legal dispute with the original book author.

At an event earlier this year, I happened to meet one of the junior VFX compositor responsible for Jade Dynasty movie but I wasn't aware at that time she was working in this project.
Because her working location is outside China I never thought of asking. Missed opportunity for perhaps getting some insider info on the VFX pipeline, oh well :)

After Noble Aspirations, Xiao Ding the author of the original novel has a fallout with NCM, the producers of the TV series.
So this movie adaptation is lead by a different company, with different stars and screenwriter.
The exception is Tang Yi Xin, who plays the same role in both movie and TV series (I think her movie character look better than her TV version).

For the historical figure, the records only mentioned his father as a Nestorian priest from Balkh (region mentioned in EP3 of drama).
However, the references he made about his grandfather in EP21 indeed suggest he is who you think. Strictly speaking, the drama hasn't contradict the existing historical records on him.

The Emperor in the drama is Wu Zetian's grandson.
The historical Eunuch/General Gao Li Shi (Guo Li Shi in the drama) previously also served Wu Zetian.

During early Tang dynasty, women did have more freedom and protection than women during most periods in ancient China. Just a few decades before the timeline of the series, there was a female prime minister (Shangguan Wan'er). The 3rd daughter of Tang's Founding Emperor, Princess Pingyang lead an army of over 10,000 men into battle. Also, free women can work in trade (weaving, singing, writing poetry, street performing etc) and even be secretary to officials (a bit like Tan Qi's role). However, a bonded servant like Tan Qi would have a very low status, until they're officially 'freed'.
However, the status of women worsened towards the later stages of the Tang dynasty.

It can be quite confusing - like RSMasterfade said it is called the 'Nestorian/Persian Church' but the historically the priests would use the classic Syriac language.
A better description would be 'Tang Nestorianism' or perhaps how they called themselves in China: "the Luminous Religion".
'Yi Si' like many characters in the series are based actual on historical figures.
We know that because his name is inscribed on the Nestorian Monument discovered in Xian (ChangAn), in both Chinese and classic Syriac.
In Syriac his (Persian) name is written as ܝܙܕܒܘܙܝܕ

You are right in that body piercings are frowned upon by Chinese in Tang Dynasty (due to Confucian/Taoism values).
But earring piercings had already became trendy for Chinese females by Song Dynasty (about 220 years after timeline of this series).

Shuang Xing is currently up to Episode 17 and apart from better English subs I haven't noticed any differences from other official 1080p versions.
The broadcaster just padded the remaining time of the hour slot with ads and other fillers. It was rated 'PG-18' but got the premiere 8pm slot.
As for Youku, if you have their top-tier VIP, they will provide 4K versions of their original dramas. so this is the version I am watching now.

On the topic of how many of the cast are also in Tribes and Empires - in an recent interview Cao Dun revealed that he had also considered Jackson Yi for the role of teen Muyun Sheng.