It's called "Blender Source Tools". Searching for "SMD" won't work.

I've added a proper error message to show when this happens. It'll be in the next release.

It seems that you have NLA enabled on your Armature, but no active NLA tracks. Use the Source Exportables panel to assign the action you want to export to the Armature and things should start working again.

Added in 2.3.

Fixed in 2.3. I've also added support for bone parents in DMX, which I didn't realise was possible until I saw those files.

2.3 includes the new import option.

Are you exporting an animation? All bones are exported in that case, as it's not possible to tell whether a mesh somewhere, potentially in a totally different file, uses them as bone parents.

This shouldn't be a problem in-game as studimdl will automatically cull bones that aren't used in the compiled model.

That should be happening already. I'll look into it tonight. Is this a DMX export?

Source doesn't support scaling. You'll need to redo the animation without it. Sorry!

No. You'd be looking at writing your own comparison system from scratch.

What you could try doing is hacking the VTA. Try replacing frame 0 with the reference mesh. There will be a bit of processing required; see the spec.