I’ve posted on this earlier.
But in summary, nibbidā has a range of senses, from “revulsion” at one end to “boredom”, “disillusionment”, etc. To be clear, “revulsion” or “repulsion” is not an incorrect translation: in some contexts it must be rendered like this. So it’s a matter of the judgement of the translator as to what works in cases where the sense is less clearly defined.
I tried using more colloquial renderings like “weariness” or “boredom” but I couldn’t get them to work in doctrinal contexts, so currently I use “disillusionment”.
Well, kind of, but it would be better to say that words in different languages have different semantic scopes. Pali/English is no different than any other language pair.