After I read the news on the recent Qt 5.9 port success, I decided to take another try on compiling Scribus 1.5.3.
I erased my local haikuports tree and downloaded it again with the newest recipes of Scribus (updated by Miqlas) and Qt 5.9.
The building process went fine after I reinstalled all the dependencies. The app was built. It runs but shows the same bug I reported some weeks ago. It creates and opens documents but trying to use any tool to make or grab objects crashes the app without any dialog.
As it was said by one of Scribus' developers in their forum above, the bug is in the Qt port code and should be fixed there.
So unfortunately no progress so far to bring this useful app to Haiku OS.