Its not too surprising that as United struggles to get planes out on time (if at all) they also struggle to make sure the appropriate language qualified flight crews are onboard the right flights. One would hope that if and when United improves operating performance that this issue would also improve.

Or, a more tongue in cheek explanation is that they absolutely are making bilingual announcements these days. One set is in Unitedish and one set is in Continentalese.