Using both, Paragraph Styles (PS) and Character Styles (CS), at the same time is common practice. The current implementation of the Stylist makes it unnecessarily difficult and requires user to switch from one style family to another.
So we should combine bot styles into one view with two tree elements. The implementation might cover larger parts of bug 90646.
Heiko, do you have some mockup for it?
It is part of this larger rework https://design.blog.documentfoundation.org/category/user-interface/ and actually WIP right now. Filed the ticket just for reference.