I use a different (although Ubuntu-based) types of Linux and I like, elementaryOS. But there are not a lot of questions on that on Stack Exchange.
Is U&L the proper place for that?
As per the U&L about page:
Unix & Linux Stack Exchange is a question and answer site for users of Linux, FreeBSD and other Un*x-like operating systems
It would appear to be on topic on that site.
Given Elementary's lineage it should be relatively easy for most people on U&L to either answer your questions outright or at least provide you guidance as to how to resolve your issue.
I would say use your best judgement. Is the problem based on other *nix utilities or something that users of other *nix systems may face? In that case you should post it on U&L.
However, if your question is extremely specific and is caused by issues in the underlying Ubuntu system, it would be a better idea to post on AskUbuntu. This is a very thin line and the best way is to use your judgement as to what fits where.