In the early part of the Central Continent arc, the protagonist was relatively weak, so Soul Hall made few appearances. Otherwise, given Soul Hall's influence in the Central Continent, it would be difficult to wrap things up. Once this volume is finished, Soul Hall and the three great magical beast clans will have more opportunities to enter the story.
As for this month's bonus chapters, there were seven for monthly votes and two for recommendation votes, making a total of nine bonus chapters owed this month. Next month should be easier.
However, on this final day of April, I used up all my saved chapters. Thinking about how I'll have to sit in my dorm room writing and building up a backlog on the first day of May... my feelings are really complicated!