Oob says that you roll a die, and that each bomber cannot do more ipc damage than production of territory. Maybe the explanation is confusing, but I would not say you must lose the max ipcs. I never played losing max ipcs in 2 years of face to face, and my mother language is spanish, so I suppose OOb are ok in that point. Anyway, a bit of logic says that even as confusing the sentence is, if you roll a die, that die must be used for determinig the loss of ipc.
Oob rules, however, are wrong in rocket attacks, because they have a picture showing the Russia AA gun attacking Germany’s IC. This made me confusing until I read the FAQ, saying the picture was wrong. If I remember right, this is the only “big” mistake of rules.