The “Active Keying-set” field only lists transformations. How someone can animate other parameters like transparency -I can’t figure this out and changes are not recorded automatically. Is it possible at all?
With your curser hovering over the transparency value press I or RMB / insert keyframe.
You can also add it to a keyset with RMB / add to keyset so you can then use auto keyframe. You can set up multiple keysets in the Scene panel.