that is correct..
All filters used in NPrinting have to be defined in NPrinting.
I have never had to use filter with SetAnalysis as i could achiewve exatly the same building expressions in Qlik with set analysis (no need to do this in NPrinting).
When working with NPrinting think like a person who uses Qlik - as a end user you do not write set analysis you only apply selections to existing fields. The same does NPrinting.