I made a complete OST episode guide with timestamps (excluding instrumental OST). It's easier for me to remember what happened in the episodes if I'm attached to a song rather than remembering whole dialogues.
Ep. 1 - N/A
Ep. 2 -
2:20 - Bu Cai - Ordinary Song
Ep. 3 -
49:52 玄鸟  萨吉 / Sa Ji - Mysterious Bird
Ep. 4 -
1:40 玄鸟  萨吉 / Sa Ji - Mysterious Bird  
Ep. 5 -
22:50 Bu Cai - Entrust the Long Moon
42:10 Bu Cai - Entrust the Long Moon
Ep. 6 -
5:14 Bu Cai - Entrust the Long Moon
Ep. 7 -
17:00 Shuang Sheng - Only You
Ep. 8 - N/A
Ep. 9 -
35:04 Black Moonlight 黑月光
Ep. 10 - N/A
Ep. 11 - N/A
Ep. 12 -
 34:40 - 黄霄雲 - Let's Be Like This for 10000 Years (要不然我们就这样一万年)
Ep. 13 -
10:06 Shuang Sheng - Only You
26:50 玄鸟  萨吉 / Sa Ji - Mysterious Bird
Ep. 14 -
4:40 黄霄雲 - Let's Be Like This for 10000 Years (要不然我们就这样一万年)
18:00 - Tia Ray - Boundary
23:13 - Black Moonlight 黑月光
Ep. 15 -
 5:18 Liu Yuning - The World I Love
12:20 - 以我之躯 - 黄霄雲 (Use Me as a Body)
30:53 - 黄霄雲 - Let's Be Like This for 10000 Years (要不然我们就这样一万年)
43:15 - 逾 (Not Exceeding) - 叶炫清 (Ye Xuanqing) (My favorite ❤️)
47:00 - Tia Ray - Boundary
49:30 - Shuang Sheng - Only You
Ep. 16 -
7:55 Bu Cai - Entrust the Long Moon
32:00 黄霄雲 - Let's Be Like This for 10000 Years (要不然我们就这样一万年)
Ep. 17 - N/A
Ep. 18 -
11:20 黄霄雲 - Let's Be Like This for 10000 Years (要不然我们就这样一万年)
21:45 Tiger Hu - Silent Moon (月烬无声)
31:40 Black Moonlight 黑月光
Ep. 19 -
14:55 Shuang Sheng - Only You
23:15 Shuang Sheng - Only You
47:35 逾 (Not Exceeding) - 叶炫清 (Ye Xuanqing)
Ep. 20 -
2:15 Shuang Sheng - Only You
15:10 Bu Cai - Entrust the Long Moon
39:10 Bu Cai - Entrust the Long Moon
46:45 逾 (Not Exceeding) - 叶炫清 (Ye Xuanqing)
Ep. 21 -
6:40 Shuang Sheng - Only You
Ep. 22 -
12:45 Bu Cai - Entrust the Long Moon
28:10 逾 (Not Exceeding) - 叶炫清 (Ye Xuanqing)
40:00 黄霄雲 - Let's Be Like This for 10000 Years (要不然我们就这样一万年)
Ep. 23 -
19:20 玄鸟  萨吉 / Sa Ji - Mysterious Bird
22:00 黄霄雲 - Let's Be Like This for 10000 Years (要不然我们就这样一万年)
32:00 Bu Cai - Entrust the Long Moon
Ep. 24 -
16:20 Zhang Lei - First Lover
35:15 Zhang Lei - First Lover
Ep. 25 -
42:10 Bu Cai - Entrust the Long Moon
46:10 Tia Ray - Boundary
Ep. 26 -
12:00 Black Moonlight 黑月光
21:45 Bu Cai - Entrust the Long Moon
Ep. 27 -
43:00 Bu Cai - Entrust the Long Moon
Ep. 28 -
17:40 黄霄雲 - Let's Be Like This for 10000 Years (要不然我们就这样一万年)
29:30 Tia Ray - Boundary
35:00 Tiger Hu - Silent Moon (月烬无声)
Ep. 29 -
3:25 黄霄雲 - Let's Be Like This for 10000 Years (要不然我们就这样一万年)
20:15 Bu Cai - Entrust the Long Moon
22:30 Tia Ray - Boundary
40:55 Tiger Hu - Silent Moon (月烬无声)
Ep. 30 -
5:35 以我之躯 - 黄霄雲 (Use Me as a Body)
Ep. 31 -
15:10 Bu Cai - Ordinary Song
20:40 Black Moonlight 黑月光
56:50 玄鸟  萨吉 / Sa Ji - Mysterious Bird
Ep. 32 -
2:35 逾 (Not Exceeding) - 叶炫清 (Ye Xuanqing)
5:55 黄霄雲 - Let's Be Like This for 10000 Years (要不然我们就这样一万年)
47:45 逾 (Not Exceeding) - 叶炫清 (Ye Xuanqing)
Ep. 33 -
16:55 Tiger Hu - Silent Moon (月烬无声)
55:25 玄鸟  萨吉 / Sa Ji - Mysterious Bird
Ep. 34 - N/A
Ep. 35 -
10:40 Liu Yuning - The World I Love
27:15 黄霄雲 - Let's Be Like This for 10000 Years (要不然我们就这样一万年)
51:00 Shuang Sheng - Only You
Ep. 36 - N/A
Ep. 37 - N/A
Ep. 38 -
16:05 Liu Yuning - The World I Love
19:05 执一念 - 黄龄 / Huang Ling - Holding On To A Thought
31:05 以我之躯 - 黄霄雲 (Use Me as a Body)

Ep. 39 -
15:30 以我之躯 - 黄霄雲 (Use Me as a Body)
37:00 玄鸟  萨吉 / Sa Ji - Mysterious Bird
42:00 Bu Cai - Ordinary Song
Ep. 40 -
33:30 Bu Cai - Entrust the Long Moon
37:35 玄鸟  萨吉 / Sa Ji - Mysterious Bird
44:45 Liu Yuning - The World I Love
48:30 黄霄雲 - Let's Be Like This for 10000 Years (要不然我们就这样一万年)

Awesome! Thanks  

Hello ! I realized something while looking for all the unrealeased BGM of TTEOTM. There's one soundtrack with violin who is also in Back From the Brink, so I think maybe they took others OST for the two dramas. And I have to say that even by looking for it for weeks, I can't find the music I searched ... Dones anyone know where I can find those please ? Thank you so much ! (Sorry for the bad english, not a native).