Harang faceup challenge

I have never painted Harang, however I've painted others with a very rough inner mouth area. My sympathy to you
Usually I choose to darken it as much as possible to conceal any uneven color that wants to happen because of the roughness. Paint will do that easier than pastel. I can use paint to fill the inner space and with a clean wet brush quickly clean up the edges that are more a part of the lip than inner lip. I think someone else will be able to explain it better.
I think lots of people choose to paint some front teeth (or not) in this situation, just depending on their preference.

I hope you can make it turn out like you want!

 

I haven't ever had to do this but for getting into small spaces, I find watering my paint down a bit or using watercolor can help a lot! You can post pics if they're hosted on a website, ie flickr! I would definitely try messing around with watered down paint and a wet brush, like AlisonVonderland suggested!

 

I've painted several dolls with semi-open mouths like this and by favorite way to handle it has actually been to pack a very dark pastel color into the space between the lips (including the lip lines) and then erase over the whole mouth with a kneaded eraser. Do this either before adding lip color or on its own layer. This should leave the space filled in nice and clean with softer edges than paint.

 

@pitzela the rough edges are definitely a more common feature of hand sculpted dolls vs 3d rendered. I agree it's really frustrating sometimes but each method of doll creation has its strengths and weaknesses. I think at a point it's just got to be hard to get areas like that completely polished with manual sanding without sacrificing details on the lips that you'd want to save. It's just kind of cool history of the hobby to me. Tons of heads out there are part of artists different journeys to learn techniques and refine skills.
Once you get the Faceup on you'll forget about the misery of it ... At least I always do until I wipe to repaint and I'm like arg I have to do this all over again!