Mario ha scrittoLook what objects are keyed in your second screenshot. It's the AnimationPlayers beneath the SpineAnimationTracks, not the SpineAnimationTracks.
Yabadabadoooh. I know what the problem is.
When I add an AnimationPlayer for a SpineAnimationTrack, the display in the Animation Editor remains empty:
I have to close the scene and open it again.
I discovered this by accident this morning. After I opened the project, all the entries I wanted were there.
Is this a Godot problem?