Hi,
Tips can't accept French accents : àéèèùâêûôîçëïö

How can I use them, please ?

This is most likely due to font you're using not supporting those symbols. Try changing the font: https://naninovel.com/faq/#how-to-change-a-font

Thanks for your answer.

My Default Font accept french accents.
The font of Prefab TipsUI accept accents.

But in Game, it doesn't work.

I see. Please join our Discord server, register your Naninovel copy (https://naninovel.com/register) and send a DM to Elringus#6359 with a repro project (https://naninovel.com/support/#reproduction-project) so we can investigate this.

I understand my mistake :
I create Managed text instead of simple .txt (for Tips.txt)
Managed Text doesn't support accents.
It works, now.

Sorry, it's my mistake.

Managed text is also a simple plain text file (.txt). Maybe the text editor you've used to edit the text files saved them with an incorrect encoding.