Help wanted on a tedious task. (Automatic Weights)

Mik Testing.blend (2.82 MB) (Tl:dr at the bottom)

Hello, I have little experience with automatic weights, but the tutorial on lips that I’m following (https://www.youtube.com/watch?v=Map_ro-xUwg&t=1517s) for my own character requires usage of them.

I know this is a common error with armatures, and that fixing it takes lots of time, and is usually not very efficient.
Regardless, help.
Whenever I attempt to parent the armature to the model with automatic weights, there’s the bone heat tracking error thingy that pops up, and I have no idea how to fix it. There are a lot of lists online, but many of them require doing things that I’m unfamiliar with.
That’s where you come in, kind hero. :smiley:

Would somebody with experience in troubleshooting this kind of error please fix the Blend.File so that the automatic weights become possible? If it may help, the only bones that require automatic weighting are the mouth bones, I would request that the other bones remain untouched.
As well, if you are patient, please explain your procedure back here in the comments.

Tl:dr - Fix the mesh to make it possible for automatic weights to be placed (for the mouth bones only), and report your procedure back here.

Edit: Just a heads up that the armature is hidden in the default file, just object mode - alt+h before trying anything.

Thanks a ton!