Are questions about the ReportServer database (the SQL Server database that is the brain of an SSRS deployment) appropriate for this site?
We have made a decision to include B.I. questions on topics such as reporting into scope for DBA.SE. Questions about SSRS are certainly welcome here. I'm pretty sure I've already seen discussion about the SSRS metadata on DBA.SE before, although I can't find it with a quick search.
In short, the answer to your question is that SSRS questions are certainly on topic for this site. If the question strays a long way into development to the point that reporting is incidental (for example how to front a SSRS report through an IFrame in another application) then it may get migrated to Stackoverflow.
Feel free to ask your question. The nice folks here at DBA.SE will do our best to answer it, or refer it to somewhere that would be more appropriate if we can't. If you have any further questions, pop into 'The Heap' chat room on chat.stackexchange.com and ask.