The wings are looking good. No, not the cores... the sheeting.

3m77 is easy to use and if done properly, shouldn't cause any problems.

It sounds like you may have spread on the Pro Bond too thick. It does foam up ad it cures, but that's what makes it work so well. Try spreading it on with something like a playing card. The wood should look wet, but not coated with a thick layer of glue. Test it on some scrap foam until you get the results you like.