without question.
Very much with question. Do a google search for “זיי נישט קיין נער” (with quotes, ideally) and then for “זיי נישט קיין נאר” and you’ll find they have a very similar number of results, and many from heimish websites/publications for both.
I don’t know about WIVO or academic yiddish but for an actual first-language Yiddish speaker it would be quite odd to spell it in a way that it too similar to “nohr/nur” (“only”) IMO and in colloquial Yiddish it is very common to write hebrew words as-is (like שבת) not because of the lack of ambiguity because many words are simply written in Hebrew. This trend is compounded by the transliteration and appropriation of many English words into Ivrit.
In Yiddish it is quite lengthy גאלדבערגער with the א…ע..ע serving as vowels,
Almost. Hungarian Yiddish (e.g. perhaps Satmar) usually leave ער at the end of words, but for the “er” suffix (and other similar suffix), Litvish or Polish Yiddish would leave out that final ער so it would be written גאלדבערגר.
Name’s aren’t a good example though as they tend to be spelled the same way as they first were written long ago but any other word e.g. “הייליגר” / “הייליגער” might be a better example.