You will not see a (converted) title in an INDB. The file doesn't open and display in the way that INDD files do; they appear in a panel.
As noted in the original post, it doesn't matter if the INDB was created in 5.5 and updated, or if it is a new creation since CS6. However, I can now report that it does matter if the INDB was created in CS6 circa May 2 or in CS6 fully updated as of now, so that's something! This shouldn't (it seems) plague INDBs I create from here on out.
That said, I have hundreds of INDBs that were originally made previous to the most recent updates, both in CS5.5 and CS6. Resaving these doesn't seem to successfully "convert" them. The problem remains.
I guess I have to hope that the next patch makes some more progress on the issue.