Try it with Craig’s language pack from here :
I’m running it on Magento 2.4.3 and it works fine for me.
I’ve just added lines like this to the end of the file fr_FR.csv to translate into French :
“in stock”,“en stock”,lib,web
“More than”,“Plus que”,lib,web
But most of the translation is already in the file.
There was also another discussion about it here on the forum : Translating Magento 2 - Installing custom language pack(s) - #14 by PawelP