Very frustrating – I did as you proposed but it rendered anything as if there was nothing happening.
I then again started fresh with the blank theme, copied everything to the newly installed theme, rendered again, got a nice and shiny updated theme but then again it failed to render changes.
After that I did it step by step but to no avail.
And after that I removed the appimage, downloaded and “installed” it again, made some baby steps – first render ok, after the second – nothing happens.
Slowly but shurely I think I give up… although I really would love to use publii.