I had this idea but the french dub is crappy

...I want to keep the english version purity for those who want it

...I wanted to ask you which software I could use...
Any advice about this ? I will make a dubbed AND a subtitled version, but without the proper software...

My translation will have two version : one with only the text translated (and so, the cutscenes subtitled), and one with the text, the voices, and the cutscenes dubbed. I will also correct some errors in the original translation (some debriefings were not translated, like the
"You are a cheater" (Debriefing 4) one in Pandora's Box, the GT Intelligence who came "to capture the Omega" while they are here for the Rasputin (if you decide to capture it) in "Avenging Angels", and many more others little things.