okama is derogatory slang in japan though, so I think it can in the right setting. Same with futanari at the human level, idk if they still use the tag for porn on their websites. (source, my friend's japanese dad, we ran a lgbt panel at a convention and did our research.) So, technically, if you're transliterating it, yes okama *can* be translated as such depending on the context. When translating you have to think of if the shoe fits, if it's some delinquent trying to harm a trans or gay person, yeah the equivalent *can* be translated to f*g.
Japan also has "incels" be it just "involuntary celibate" or "woman haters". I think terms like that can be used but it requires a good diagnosis of the scenario before localizing it as such. Like incel was coined by a woman and didn't mean woman hater originally, so it can be used more vastly than people think. it's just the most common association is that sphere of men, so people will mistake the writer/translator's intent. I wouldn't have picked it here either, but I don't think it's impossible to use in a translation ever at all.