for my project (www.pypapi.org) I use a print templating based on the xml saved from OpenRPT (great project!).
The PyPaPi server has not a X-system with QT, so I have writed a small python xml processor that compose a pdf canvas using the reportlab python library (www.reportlab.org).
For now it implement single header and footer, label, field, line, but not images and barcode.
The main code of this "layer" is here:
And some other information (italian) here:
In future I intend to expand this "wrapper", maybe in a separate project from PyPaPi.
bye, and good job!
[¹] a Italian software for the Public Municipality