I've definitely run into #1 on the list. "Paamayim Nekudotayim" is a transliterated version of פעמיים נקודתיים, which means "double colon" in Hebrew. Zeev and Andi are Israeli, which kind of explains it, but the error message is still pretty useless.
Its only a "bug" because there's an unspoken rule that all programming languages should be written in English, and English doesn't have a proper word for this symbol. Pretend that English had no representation of an ellipsis, but Hebrew did. Should the language author say "Expected: dot-dot-dot" in the error message to appease native English speakers, or should (s)he use the unambiguous form?
This isn't about whether we use English or not, or whether that's the right choice or not, it's about consistency. If you want to create a language that has all-Hebrew tokens and error messages, knock yourself out. Just do it consistently.