As a non-native english speaker, I just add it to my usual research, with a bit of intuition thrown in. It's good to have in mind the origins of words that get used negatively in general - calling someone an ass is likening them to the animal, a bastard is likening to someone born from cheating or a disapproved relationship, etc etc. I use this more to remove Christian-based expletives out of my comic since it's a different world (eg; "bloody hell" makes no sense there, they don't know what's so special about it being bloody), but the same applies to insults and slurs that might develop over time.
In Brazil, ableist language is like, everywhere, as far as idioms for titles (a common one is "deu a louca no X", which is a bit like "X has gone crazy" which gets used for any deviation of the normal trope or character), buuuut... I'm in English spaces enough to know I should be avoiding ableist language, so I always try to look at those scenes with care that I'm not using words out of habit. And read, reread, etc etc. If you get a feeling the word you're using might be sus, google it or its etymology, and err on the side of caution if it's not quite bad but still easy to misinterpret.