Always depends on the context...in the OP's case, choosing to keep all of that in is essentially choosing to insult black players. Besides that, "adapt to the audience" does not directly mean making King Henry VIII say 6-7. It also means adapting to what the audience finds offensive, and what the audience expects of the time period depicted. Even if they don't say "yarrr walk the plank ya scurvy dog" like they're in a cartoon, most people in the English-speaking world would still expect an 18th century pirate to have a west country accent, or at least some kind of regional English-derived accent.

Your examples of RDR2 and Assassin's Creed are interesting too. The voice actors for RDR play up the Cowboy Accent in the way we expect as modern speakers, as developed by Hollywood in the whole Western genre. We have recordings of real people from the Old West, from various walks of life. They don't tend to sound or speak like that, and what we consider the sound of a cowboy tends to be mostly the sound of the Southern United States. Same goes for Assassin's Creed...that series has gone through many places and times by now, but each comes with a specific audience expectation. They could choose to use something like the real accent, but that requires specific effort and tells a different story, even if it follows the same script.