Artist / Album information Sources

First: I don’t currently use Roon (I use Plex) since about half of my listening experience is on the go and Roon doesn’t support playback outside of your lan yet (or ya know… I would be listening on the go, if I wouldn’t be bound to my home because of our cute little corona epidemy). But I want to switch to it, as soon as they implement proper mobile Support.

With that being said, my other big consideration is the metadata sourcing. Namely, which sources does Roon use for Album and Artist Information? And can I force Roon to globally only use local Album arts? I currently have a 60K Titles Library which consists exclusively of Japanese Songs and Plex convert my entire Library to a complete Clusterfck, since Plex Metadata sources really don’t like Japanese Artists. My hope is, that Roon is able to do a better Job with my Lib.

Last time I checked, both Roon and Plex used the same sources (AllMusicGroup and MusicBrainz).

Yes and no. It has a global setting that allows you to prefer your own album picture.
There is no way for local pictures/metadata only (not a feature of Roon).

The setting is in Settings → Library → Import Settings.