AU gets more traffic than U&L, I think, I think1, 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.
1 We do get more traffic: http://stackexchange.com/sites#traffic
About 400k visits per day for AU as opposed to 168k for U&L. SU has a higher rate at 640k+/day and better answer rate (72% vs 66%). U&L has a much higher answer rate (82%), but IMO they, like SF, are stricter on question quality (not a problem in your case, I'd think). You could try on SU, but I'd think the experts on Linux are either here or on U&L (probably both, as I have seen a lot of familiar usernames in U&L in my brief forays there).