This episode is really a filler. As someone who has no prior knowledge to this or the original IP, I can't really say much in terms of whether the characters are accurate or not. I can only objectively rate what I've seen in the anime. And for a 12-episode anime to have a filler episode that isn't that particularly needed for the main story is a bit weird. The animation isn't the best. Even the action sequences, considering that this is an anime about muskets, the action should be higher or at least better executed. But unfortunately, neither seems to be the case here.