Feed43 is based around pattern matching - it mostly assumes a well-structured HTML document with predictable tags, and it's that method for every site.
You seem to have some sort of custom plugin architecture, I guess?
Exactly, mine is really only focused on sites that are either hard to scrape (login, blocking, not well formatted,...) right now. So either site you want to integrate requires a custom plugin. It's pretty niche but the repository can be found here in case anyone is interested: https://github.com/dewey/feedbridge