AU gets more traffic than U&L, I think, but I'd say the major cause of your problems not getting attention are that they're in tough areas. I see `pulseaudio` in a question, I tend to mentally block it. I have fought my battles with it and lost spectacularly.

>If the question's scope applies to non-Ubuntu distributions, does it belong to the Unix and Linux site?

Not necessarily. If at least one of the platforms actually involved in the question is Ubuntu, and it does involve the OS in some way, you could make a case for it being on-topic here. There are exceptions. For example, if you have dual-booted Ubuntu and Mint, and want to get something on Mint working, that is off-topic here.

You could try asking elsewhere, but if you do, remember to delete your questions here. Cross-posting on multiple SE sites is not welcome.