I won't pretend that the Linux package names might not stay current. Adjust accordingly. They worked when I created the document (back when python3-* still got you Python 3.3.x on ubuntu/mint), and I always tend to assume that Linux users are fairly resourceful and resilient (as it indeed seems you were
). I'm not going to be chasing exact linux package names, nor updating the documentation every-other week.
The list of additional Python modules needed for a complete Sigil plugin environment are not Linux software package names, but rather, they are the official Python module names useable with pip(3) or easy_install to install from the python.org Python Package Index (pypi.python.org). Since not all Linux flavors use synaptic, I chose to list the additional modules in a distro-agnostic manner. 'pip3 install Pillow' should work on just about any flavor/version out there.
Not being a technical writer, it was never my intention to create a document that someone with no experience with Linux package-management and/or little to no experience configuring/building/compiling software on Linux could use to easily build Sigil with no effort. It is primarily a guide for those with the inclination/knowledge who just need a push in the right direction.
I'm happy to offer assistance, however, when Linux users with questions come here to ask for it. It happens quite a bit, and there are enough Linux Sigil users around here that they rarely have to wait long for help getting it built.
Glad to see you adapted and overcame the document's limitations, though. Seriously. That has always been my hope for a document that--if I'm entirely honest--I hated every second I spent creating.
If anyone wishes to contribute detailed, distro-specific instructions/tips for building Sigil from scratch (or instructions for installing Sigil 0.9.x from distro-specific repositories), I would happily include them in a compendium of user-contributed instructions that I could link to from the BuildingOnLinux document.