I mean on singing though they have talked in English, but it's not really common. Nayeon is currently taking English classes, Mina is already pretty good at English, and Jihyo sings the best in English imo. With Jihyo's voice, I kept thinking that Jihyo was the most fluent in English and one of those idols who moved to an English speaking country and went back to SK for training. But that probably wouldn't be possible with her because she started training at age 8.
Also, I heard that Momo used to be very fluent in English but she hit her head and doesn't remember much now. Momo is really sweet and she likes to speak English sometimes, her accent is really cute. She said it's coming back to her and that she's getting better too. Tbh, I couldn't imagine fluent English Momo but I mean, I could imagine it.
1. Jihyo - she sounds like she lived in Southern United States of America for a while, even though she has an accent when she rarely speaks English but I heard that she can read and understand English well. Probably the same with most idols but they aren't too confident in speaking it.
2. Mina - Mina sounds very fluent in English whenever she speaks it or sings it. Why I didn't put her on top is because she has a rich accent.
3. Momo - Momo sounds really cute and I was debating about this but it kind of sounds like she doesn't have an accent when she speaks in English, but when she sings in English, it sounds like she has a very rich accent.
4. Nayeon - Nayeon has an accent too but she sounds like she speaks European English for some reason when she sings in English lol.
5. Dahyun - Dahyun sounds like she has a American accent when singing, she has a heavy accent when speaking though lol
7. Sana - Her voice is really cute, I can't imagine her singing in complete English and when she does she has a heavy accent but it feels like she has almost no accent when speaking in English for some reason.
8. Tzuyu - She sounds fluent when speaking and singing in English and she's really good at it.
9. Jeongyeon - She has a strong accent when singing and speaking in English but I guess she could pass as being from an English speaking country. She also emphasizes her pronunciations for l's as r's.