I saw this this morning on tablet, but hate responding on that thing. Mind you, the doc this morning also said switching which hand I mouse with might be helpful, so desktop is going to be no picnic for a while.
TOB has not been published in years. It is fully operational at generating JS files for 2.93. There is just a lot of extra stuff to support my workflow. like skeleton pose library JS generation which only supports my animation system.
It also has an additional pre-export stage to either do mesh joins by parent or material. I use it to be able to export blends which have 70 meshes down to 12 by material, pick which meshes are the host mesh & any meshes to be excluded, yet still store it as 70 meshes for editing purposes. It is not something I feel that I want to support / document.
Finally, I want to and have in the past changed what the source generated is without taking anything but my own needs into account.
The logic for handling multi-materials is identical in the JSON variant. Embedded graphics is really out of step with the mainstream. Very powerful, but not for the novice. It was probably a mistake to publish in the first place. I am not going to repeat that, sorry.