So you can't use setColumn, setRow and setPoint etc when using Parola?
No. Parola is likely to rewrite the entire display, depending on the animation used. So the safest is to assume that Parola has complete access. If you want to mix text and graphics, you need to manage it all yourself and you can do that through just using the MD_MAX72xx libraries. There is an example of scrolling text display for that library.
Need a displayClear(uint8_t z) method or is there another way to clear a zone?
I thought there was. If there isn't there should be as an overloaded displayClear(). Will check over the week end. In the meantime just clear it by providing an exit animation from the zone - that will leave it clear.
EDIT: overloaded displayClear() has been added and will be in the next release. The method is available in the source code section for download now - MD_Parola.h is the only file affected.