You're having more luck than I am. I set up PCLOS as a Virtual Machine and sigil won't run at all. The version of sigil installed via synaptic is built against Qt5.11 and the version of PCLOS I have is on Qt5.12.
sigil-0.9.10-1pclos2018.x86_64
EDIT: I take that back. Much of qt5 is uninstalled. The sigil package lists python3-lxml as a dependency, but not all of the qt5 pieces it requires. That's a little silly.
EDIT 2: it also installed Sigil's supplimental material to the /usr/share/
SHARE prefix.
That there will break tons of stuff.