Thank you for your answer and your advice !
Sadly, our users already have the device's culture set to the needed region and they are already using the corresponding keyboard.
It's more a cultural thing : even if French language contains accents, most people don't type them when using a smartphone since you have to hold a specific letter or choose an "adviced word" by a given dictionnary. It's slowing down the process of typing if I may say and we thought, it would be more user friendly to have a SuggestionMode being accent insensitive.
Anyway, it's alright ! We will implement a tricky solution on our side to achieve such result.
Thank you for everything and wishing you a good day !