The fact you got two responses is good. How many queries did you send?
Your basic approach seems fine. However be aware there is a difference between and agency and a management company, so change “agency” to “company”. Also I would not include “French screenwriter”. Just get to the logline as quickly as possible. The fact you are contacting them lets them know you’re a screenwriter who’s written a script.
The fact one company did not get back to you, not surprising. How long since you sent your query? Sometimes they can take 4–6 months or longer. Or they may never get back to you.
My advice: Keep writing more scripts. Don’t rely just on one or two. And keep querying, but in a strategic manner as I suggested in the original post.