You can completely disable Roon’s metadata database’s influence over an album by doing:
Edit->Identify Album->None of these Look Right->None of these Look Right->Use Basic File Information
The “Prefer Local Metadata” features mentioned above are a softer measure that guides how metadata from our databases are merged with data from your tags.
I encourage you not to think of Roon as an editing/grooming platform. We may grow into that over time, but are not there yet, and there is plenty of good software for tag editing. With clean file tags, you can get a fairly rich result, particularly using FLAC, which has the most powerful tagging structure of the formats we support.