Just a thought...
I see you are using a template called
myMTDoubleSlide
Maybe you could try changing that to
modern , just to check?
I am guessing that your template for the comments may be from a previous version that isn't adjusted for new fields?
Just guessing as I said... :/
Cause I tested the original
MTDoubleSlide that follows the package, and that worked, complete WITH translation fields.
I also renamed the French translation to my language, and uploaded it to test, and it worked easy!
Are you sure you are putting it in the correct folder?
It should be placed here:
www.mccr78.com/language/fr-FR/