Thanks for your patience and persistence here. I see you and I agree the dialog is a problem in general.
When I've designed forms with repeats, I've generally either worked around the dialog or provided an instruction screen before it appears. See XLS form- Repeat select_one question until "A" is selected - #12 by LN and other posts in that thread for ideas.
I think I agree with you that the language change could be an easy improvement. It would help to hear from other users about whether that's the case or not.
The challenge is that no real conventions have been established around repeat naming. Some people use a singular noun (observation), some use a plural (observations) and others use phrases (add an observation). I think it's going to be hard to build a sentence that will work well for all.
I'll also give some thought to making the full prompt text customizable. I think the challenge there is making it translatable.