Q: Ça fait 3 mois que j'apprend l'anglais. は 英語 (アメリカ) で何と言いますか?
A: That makes 3 months (now) that I’ve been learning English.
Q: Ça fait longtemps que je ne l'ai pas vu. は 英語 (アメリカ) で何と言いますか?
A: It's been a long time since I saw him/her
Q: "Ça fait 3 ans que j'en fait, et toi ?" は 英語 (アメリカ) で何と言いますか?
A: I've been doing that for three years. How about you?
Q: en fait je préfère ne pas y aller は 英語 (イギリス) で何と言いますか?
A: In fact, I prefer not to go there.
Q: J'ai fait une gaffe ( like a little mistake not important "oops" ) は 英語 (イギリス) で何と言いますか?
A: You can literally say 'I've made a gaff.' Also, 'I've made an error', 'I've made a mistake', 'I've slipped up'.


Q: How do you say "J'ai fait ma rentrée scolaire en septembre" in English? (I completed the start of the school year in September)
A: Ah, I missed that word!

The correct version is:
I made my return to school in September.
I came back to school in September.
I went back to school in September.
(“Came back” implies that you are at the school currently.
“Went back” implies that you are not at the school currently.
“Made my return” is neutral.)