Is having multiple SQL db's a bad idea for a single application?
Certainly not anything inherently "bad" about this approach. In fact, it's often a good idea and in your case sounds like it probably is. You can possibly get performance gains depending on how you create and open the various databases as well.
A couple specific pointers:
- Static Data: Since this database is read-only, open it as read-only
- You can can actually join across databases like: Use the ATTACH DATABASE SQL statement and go from there.
Before using two databases, I would think about having one or two JSON files. It may be ok for your Static Data, and will probably be enough for metadatas.
Obviously, it depends on the quantity and organization of your datas, and if you do or not crossed CRUD operations.
I'm not familiar with iOS, but I'd consider it from a space standpoint. What's the minimum size of an SQL DB vs. the size of the data you're going to store in it? If the DB doesn't add a significant amount of overhead, then it should be fine. But if you're going to be storing 1K of data and an empty database is 16K, I'd reconsider.