I have definitely heard some people on the modular route who firmly believe that there's a maximum number of schools an airline employer wants to see on your CV. I've not seen any hard evidence of that myself, so suspect that if true at-all, it's probably just a small number of airlines.
If you do have target airlines, I'd suggest checking their recruitment policies to play safe, but it is hopefully a non-issue.
How did you do the ATPL exams without a PPL? Unless things have changed since I did mine in the late 2000s, you had to have a PPL before you could be accepted on a professional groundschool course.
G