When you right click on an item in the plugin list, either as an fx or in the plugin tab, you can add it to your favorites or group/ungroup it. I’d like to know what file this stuff is saved to, ideally so that I can just do this using a text editor rather than manually clicking on hundreds of plugins and also so that I can backup or delete my custom plugin hierarchy. I’ve tried finding a file like this myself but I can’t do it and if this was mentioned on the wiki or here in the forums I haven’t found it.
The information is stored in CachedVST3S_x64.db in the config-directory of renoise.
To elaborate on this, it’s stored as an SQLite database, not a text file. To do what you want would probably be painful without a dedicated tool for this specific purpose.
You can probably very easily vibe-code a small xrnx tool that creates a dialog for exporting/importing or even edit this kind of information.