Now, if you think you can improve things, please go ahead. I'm not a pixel artist and I probably don't have the knowledge to fix the things you might report here. That doesn't mean you can't say anything about that work, this is always appreciated. Communication is one of the best tool on earth we have.
On my side, this tileset is pretty much finished but minor fixes are greatly wanted if needed however I can't spot where these possible fixes are needed. I agree that the palette is really big but this tileset is really good compared to what we have currently in game so it might only be a minor thing to worry about. I also wanted to say that we currently do not have any interior or fringe tileset for the castle but before this tileset gets forgotten once more, I suggest we fix it until it gets pushed.
Hope I helped,
Ali-G