The Great Vowel Shift in Middle English should be well understood by a computer system given that it happened centuries ago.

“Long a” (in most European languages, this is “e,” and I can’t be fucked to look up the IPA) and “short a” (closest I can come up with is “ä” in German, though the throat positions are different) were literally taught to me as the educational term in first grade.

If the training corpus is so poor that what a 6-year-old understands in the '80s is utterly baffling, NLP hasn’t advanced near as much as it should have.