A really common issue with sway is that it doesn’t run as a login shell, so none of your .profile or other environment settings get sourced when you login. I think that might be the problem here.
Try closing your sway session, then login to a tty and run sway
. If the qt themes work properly then it’s definitely an environment issue.
Not sure if sarcasm or actual disinformation. You’re not supposed to trust the aur, that’s kinda the whole point of it. The build scripts are transparent enough to allow users to manage their own risk, and at no point does building a package require root access.