TYPO3 Core

I've corrected the description from

AT TCA you can find defined search fields for the meta data of files, but you can find files searching for meta data.

to

AT TCA you can find defined search fields for the meta data of files, but you can not find files searching for meta data.

Yes, this is wanted behaviour. The search uses the list module to display results and that reacts to the configuration of which tables to display - if you remove the hide table from TCA those records are actually found. I'm going to close the issue now, as this is not a bug. However, if someone wants to implement an addition to the search to be able to search and display files (and metadata) in a separate view, please feel free to do so.