The issue with French and why it works so badly is the assumptions people made when designing the speech-to-text by starting from English. The core issue is that spoken French and written French are two completely and widely separate languages, with a much much greater difference than English. So the current approach to try to use books and mapping words to them isn't just working well.
What I mean is the current approach is pretty limited.
Written french is largely codified by the french academy which is very conservative (so the written language did not evolve much in the past 100 years) whereas the spoken language evolved independently. It's a bit like slangs in English if you want but to a whole new level, the two parts of the language don't have much in common nowadays. Tenses, pronouns, grammar, sentence construction and words are different.
It’s hard for me to believe the they have diverged that much. I’d expect that the one would drastically influence the other. But then I don’t know French.
What I mean is the current approach is pretty limited.