Like manga, I hate it when they, for example, transliterate さん as -san, when there is an “equivalent” word for it, like Mr. but would it carry the same connotation as the source material? I cringe when I buy translated versions of Japanese literature due to this (which is why I stick to the source material), it just… does not sit well, I mean instead of writing -sensei, -senpai, or -sama there are “equivalents” in English for those but the catch is that would it work well upon translation?
They’re kept because it’s what everyone is used to. It would feel weird to have them say mister when we wouldn’t. But if they use -san, then it feels normal.
They either keep them untranslated or just drop the honorific entirely. Anything else would not feel well while reading.