There has to be at least like...
1-3 chapters for regrouping/everyone healing up and getting their resolve back.
2-5 chapters on what Juha's effect on the world is, the missing presence of the soul king, and some backstory.
1-2 chapters going into Juha's door.
3-7 chapters for the final fight.
2-5 chapters for cleanup/epilogue.
So...8-22 chapters left if we want a good ending.