I think it's a bug with the set_coa command, but just a minor one (perhaps visible too with Italy, Hungary, etc. which change their arms). What I've noticed is that if you save a game, and then reload it, the COA *might* not be the right one as when you initially started. In that case, exit your save, go to the start date that your save was in, and load that. The CoA will be reset Then, exit that, and reload your save from before, and your CoA is good to go. I think it's a slight glitch with the command in that it isn't always recognised to reset at particular dates in the history but it's not game breaking by any means. It should work for latest version.
Your case sounds like some weirdness with the King having been overthrown and everything switched back. It should be dependent on the date on which you start, primarily, not so much with who holds the crown, but who knows what can happen if a game decides to glitch?
By no means is it too annoying either, I think, but I've noticed that as well. It's just a minor fuss, but there's easy workarounds to it!

Glad you like it, Nik! Certainly wasn't simple but not too difficult to make either!
