It may or may not. But, whenever she checks in they will confirm the details that they care about for that segment of the journey. IIRC it's really only the US TSA/DHS that cares about DOB and even then I don't think they will reject anyone for booking a ticket with the wrong DOB (as long as you can produce the correct one on-demand). I would think that incorrect name spellings, DOB, nationalities, etc are fairly common I think especially since a good number of travelers don't do their own bookings. My firm's own travel agency usually just makes up DOBs for folks if they aren't provided and I've never heard of anyone having a problem.

My partner has had my birth year in his UA profile since 2012 and we've never had anyone even mention it at check-in, immigration, or security. I wouldn't worry about it.