Probably built 10+ importers, plus some plugins to do automated transaction annotations.
I have not made any update for many years now, because: - Downloading statements is still a pain, have to manually go through all websites. Banks are bad at making the statements available, and worse making it possible to automate it. - The root of the issue is actually that beancount is too slow. Any change/update takes ages. Python is both a blessing (makes it easy to add plugins/importers etc), and a curse (way slower than some other languages.
I believe the creator of beancount has started working on v3 with a mix of C++/python, relying on protobufs, a C++ core for parsing, etc. AFAIK, that is not production-ready yet.