Problems are regularly reported on Village Pumps on-wiki. A big part of the Bugmeister's task is getting the problems brought up on Village Pumps addressed by the Foundation. Following are some of the best ones I've found.
If issues need to be reported on Bugzilla, then using the {{Tracked|bug#}} template is especially helpful. Copying issues to Bugzilla and then following up with {{Tracked}} template can help other users see that reporting issues in Bugzilla is one important way of getting issues addressed.
I'm including the Wikis here that I've posted on. Sometimes using a translation tool like Google Translate, Chrome's Page Translate or gTranslate is very helpful. It may be necessary to import the exported Template:Tracked
For a complete list of wikis, check out the targets list for Global message delivery.