Hello bullet-dodgers,
I intended to join in last year but got distracted IRL. I was going to use this as I ported it to godot at the time: https://github.com/spaceyjase/godot-bulletml-prototype
…which also now works in godot 4, if C# is your thing (and can be called from gdscript). Markup itself is documented here by its creator:
https://www.asahi-net.or.jp/~cs8k-cyu/bulletml/bulletml_ref_e.html
Fingers crossed I get some time to join in!