My wife's passport says her full "Peruvian" name...."Erika-Rosa-Paternal-Maternal-de-My last name". My lawyer submitted the immigration paperwork as her "American" name...Erika-Rosa-My last name. Our interview is coming up. Does anyone know if I should have her change her passport? Or if the name differences will be a problem at all?

Likely not an issue. The visa will be glued into the passport so there will be no question it is hers. Her US Immigration paperwork "name" will be what official documents refer to her as and what her EAD and other documents will have on it. This is a common thing for asian countries as well (names do not conform to US naming syntax) so you are not alone .

What if I file for the petition with Paternal-Maternal-de-My last name will the government just conform it for her to my last name?

Thanks for the help, random man. That's one less thing to worry about in getting ready for the interview.

Shouldn't be an issue. My husband's says "M____ M____ C_____ A______" but his green card and everything else just says M____ C____

They understand names are formatted differently - while the DMV may not, immigration never gave us any issues.