hi medmedin
of course the ppa is (very well) maintained!
and will not disappear anytime soon.
as i wrote in a previous post, the problem is not at all with scribus, but you seem to hit a issue with the packaging by debian of one of the dependencies of a dependency.
there is nothing scribus can do and it's very likely that it's a matter of time before it is solved.
i also downloaded the current appimage of trunk and i could not see any flickering nor could i see any bug.
i'm involved in maintaining the appimage for scribus and i don't see how it could be full of bugs.
can you be more specific?
did you try the nightly appimage or an old one?
concerning the speed, the appimage should not be much (if at all) slower than scribus as installed by other means. it's exactly the same code.
it will start a bit slower, since it needs to first unpack the files, but on my machine it does not make much of a difference.
of course, under some circumstances, it will require more memory than other types of executable.
but it should not be much more than scribus requires on macos or windows.
(so, if you don't have much memory it can be slower... yes...)
also, a few days ago i have successfully installed the trunk ppa.
i have now tried to track the dependencies from here:
https://packages.ubuntu.com/eoan/libopenscenegraph100v5 and i could not find a package that is mandatory *and* cannot be installed.
but i did not see any pre-depends either...
and from what i can tell multiarch-support has never been in 19.10... and i really can't think that the ubuntu folks will be removing a package after a release is done.
you seem to have more issues than the average user...
and the fact that you have now installed the multiarch support from a different source, let me wonder if you haven't done similar things in the past and made your system unstable...
if i were you, my next try would be to setup a fresh virtual image with the latest ubuntu and install there the ppa...
(and i would have done that before adding "foreign" packages...)