I read your question with interest, it is quite logical that I do not let you sleep, I think I can offer you a solution.
After doing everything you describe, you could manually search your system for all traces of the program, you know.
For that, install "tree" and do the following
tree | grep "program"
with that you will ask for a ...
Looking over the installer checks and seeing it uses lsb_release, i can suggest a 'dirty' way of bypassing it and making it return what it needs to in order for the installation to continue.
You can try editing the /etc/lsb-release file and make it look like the one from Ubuntu 18.04, something like this:
Remember to revert the changes after the ...