Gems of War is working quite nicely on Steam Deck; the only aspect of the game that is extremely annoying to use is in-game chat (you can’t see what you’re typing, so if you have “fat fingers” and typos are your best friends - don’t even try chatting from there). Other than that - everything works as it should. I’ve been playing GoW on Steam Deck on and off for about two months, maybe a bit longer (interchangeably with playing on an Android phone and on PC as well), without any problems. Not from the game itself, I think it crashed once, but not since. And not from the devs. I was a bit nervous at the beginning, worried about the anti-cheat mechanisms as I like my account as it is but clearly nothing was triggered.
I didn’t think of a ticket, to be honest. I thought it was related to how the keyboard works on Steam Deck and couldn’t be changed, and I haven’t played any other game on it that would require keyboard and typing. But from what you’re saying, it is fixable. So, ticket incoming.
And with the devs - I assume exactly the opposite. Steam Deck is not yet available in Australia, so unless devs got it outside the official distribution channels, I doubt they have one. I hope for a response other than “can’t reproduce”