Not cursed... gremlin's maybe. Sounds like you have a Friday afternoon head unit and AC control system right there. You're posting here asking what to do? It's broken - you want it fixed - seems like you have already made your peace with the price and will take it in. Knowing others have had similar issues won't lower the invoice even if you could say there's dozens of others on the forum on the internet you read about. Unfortunately.
So if you search there are people who have had odd audio issues, I think I have read about some where they volume goes down and others who have white noise scream out of the speakers but I think that was an amp issue. Bottom line is it's not a very common fault but it sounds to me like you have one with a cracked circuit board or bad solder joints.
If I was in the same difficult position you were in, since you can 'fix' the display by pressing around it - that helps locate where part of the problem is. Do you know anyone who can solder or is good with electronics? I would be taking a look at the boards in that thing and going over them. You can also try appealing to Subaru of America and explaining what's been going on with it, you may want to try this first... the tinting may have broken your rear defroster but it wouldn't have damaged the head unit/AC control. It does seem a bit unfair so be polite and keep nudging them to see if they will respond - many on here have had some luck out of warranty by appealing up to SoA about issues.