OK Thank you for pointing this out. I’ve now changed the box header to the main category so to speak.
What I’m actually looking for is a way to get every parent category shown as a box header in between all the child categories (like in my previous screenshot).
Is that possible at all or should I then make search instances for each and every parent category separately? And use all the shortcodes below each other in the sidebar? Will that work at all, I’m wondering…?