I eventually managed to get Scribus built. It actually runs, quite snappier compared to version 1.4.6, but it crashes when clicking any tool (Text, Shapes, Lines). So it's basically useless until these bugs get squashed.
I hope the work on this port advances since Scribus would fill an important gap of killer apps in Haiku OS. It's a full featured DTP app that can handle text editing, vectors, page layout, PDF form creation, PDF for print output etc.