I'm aware that FileBot isn't intended to edit metadata, but I assume you guys are my best bet to find out how things work.

So, as I found out, {tags} seems to include tags that aren't in the filename but in the tag "tags", too. I have a few files that have that tag filled, so that's how I realized, but what I haven't figured out: How could I edit this tag in my .mkv file?
I tried MP3Tag, MKVToolNixGUI and mkvpropedit, but while I could edit a few other tags (say, "Comments"), I haven't found a way to edit the "tags" tag. It's also quite hard to search for, as ... well, a tag named "tag" doesn't really help with that.

If you're not sure how to see the tag: In Windows, right-click an .mkv file -> Properties -> tab "Details". There it shows the properties "Title", "Subtitle", "Rating", "Tags" and "Comments" under the heading "Description".
Any suggestions/ideas?

Thanks in advance!