To be fair its super to disconnect as making guesses based on what you know as a reader and what the actual characters would be seeing. To them, if it looks like a duck and quacks like a duck then its a duck. She says shes a man, talks like a man (even though it doesnt seem like that in english) and looks like a man so they only have one conclusion to draw where we have so much more info
Yeah, the English Language doesn’t really have Pronouns that are specifically gendered. The Japanese language has male (ore), female (Atashi), & gender neutral (watashi). This whole time she could be using male pronouns and rough language normally only used by men and we wouldn’t know while reading it in English

idk man, so far she havent, in the slightest bit, behaved like a man to me. like even though she might look like one, its kinda weird that no one figured that out yet (except the old lady since i think she touched her boobs)