Naive , Dumb Female Lead

FLs that are young, a bit naive, and not particularly studious or intellectual, but they have lots of energy, they aren't jaded and their hearts are in the right place:

• Hi! School - Love On
• Koi wa Tsuzuku yo Doko Made mo
• Ashi Girl
• School 2017
• Attention, Love!
• A Love So Beautiful
• To the Beautiful You
• You're Beautiful

Kahogo no Kahoko, which is already on your ptw list. I don't think she's dumb, but she is VERY naive. It's kinda amazing that the character is coming across as believable and not annoying, which is very much to the credit of the actress, Takahata Mitsuki.

If you're into older movies, Lily Carmen of Carmen movies is genuinely dumb :)

https://kisskh.at/13797-carmen-comes-home

https://kisskh.at/43979-carmen-falls-in-love

 GentleRain:

Lair Game (japanese version)
You Are Beautiful
Itazura na Kiss (and all the other versions from Japan to Taiwan)
Perfect and Casual
Goong
Princess Lulu
Pinocchio

I Watched Goong , FL is not dumb , watched all the Itazura na Kiss versions , the TW version is the worst one  where the FL is unbearably dumb and genuinely retarded