Yes, definitely the NHL has to approve everything and make sure it is within specifications. I'm also sure someone from the team has to at least look at a rendering and "approve" equipment and colors as well. I had a friend with a Ron Jeremy themed painted mask, I'm not sure if that would be okay. 🙂
David Gunnarsson of DaveArt does Jonas' masks. Doing a search, I see an Amerks mask, a couple of Brynäs masks, and the mask he wore last night. It looks like he wears Bauer masks, which are handmade by Pro's Choice. Goalie equipment is a personal thing and teams usually just pay the bill and don't have input. I'm sure Pro's choice may have already sent a ready to be painted mask to Dave to get painted if Jonas desires to have one, it just takes time. Just an FYI.