Do you know whether or not its the case?
that's not the case, nope :(. it's been confirmed by the author that Klaus' route is "on hold" until they're sure that they're gonna do a good job with it. rn, D2's end is where the route stops and there's no content beyond that (even if the lack of a credits scene would imply otherwise). soooooo unfortunately, we'll have to wait for more Klaus content, as rn there's no way to open that door. but his route will be expanded on the future! ;)