Is this an unfair/offensive request?

I am American. I’m living in the UK. My current roommates are Spanish and Italian. Two are moving out, so now we’re filling those rooms. I would like to have another native English speaker in one. Of course I don’t mind slowing down, but constantly speaking English incredibly slowly and “dumbed down” is really exhausting! Sometimes I want to just speak freely, without carefully choosing words or enunciating, you know? We’ve already chosen one roommate who’s also not a native English speaker, and I’d like to express this preference to my flatmate but I’m worried she’ll find it offensive. Surely she can understand, since she must have experience slowing down her Spanish, right? What do you think?

Thanks!