itch.io

I know this is 2 months late BUT my pleasure to help. Thank YOU for creating this. It's an incredibly handy tool. 

Alright - figured it out. 

Itch.io version of the plugin is outdated. If I click "download now" at the top of the page, go straight to downloads, and select itch.io v2, it gives me a version with a python script that is only 300-some lines of code. While directly downloading from github gives me a script that is 500-some lines of code and aligns more with the description above. 

I believe it's the latest unless you've made changes since last friday. Maybe I somehow grabbed an older version than v2. Let me take a look.
Side question - is the newer bone structure and naming different than the one you've posted in the description above?

Not sure if it's user error, but in 4.5.3 i've had issues with the "prepare rig for godot". I'm using the human 5 fingers godot rig. The naming scheme doesn't match the scheme mentioned above. 

WHAT A BANGER