I've improved my script and it's now capable of backing up a tapas comic regardless of the number of episodes or pages per episode.
It backups in a sequence of pages: 1, 2, 3, 3.1, 3.2, 4...
All you need to do is supply it the source containing the links to all episodes, that is something that needs to be obtained manually since it's loaded by ajax. The links can be mixed within other HTML, it doesnt matter.
I just backed up Undying Happiness as a test and it worked like a charm.
Way better than what you'll get from wayback machine 