If someone contacts you and informs you that something did or said offended them, then politely apologize and modify your behavior accordingly. We're all friends here, and friends respect each other's sensibilities even if they're not shared.
This is not a bad rule of thumb, but it's also not complete. After all, that gives anyone who wants to give someone else a hard time a very simple way to do so: just claim that everything they do offends them.
See, there's another part to the rule besides "don't unnecessarily offend people." That part is "don't be unnecessarily easily offended."
To be absolutely clear: There is
no prohibition within BattleMaster on roleplaying any kind of absolute bastard of a character, whether a sexist, a speciesist (racism would be pretty out of place, given that there's never, to my knowledge, been any explicitly roleplayed different races of humanity), or one who suffers from any other kind of ugly prejudice or nasty character traits.
As long as they abide by the general rules of roleplaying (that is, broadly, don't do anything bad to someone's character without their explicit approval or the game saying that it happened), it is
up to the players to marginalize, ban, and otherwise ruin such characters in an in-character manner.
So once Taselak has a government, petition to have Fen'Harel banned. It's a small island, and no one can leave; a character that makes itself a pariah isn't likely to live long.