Is the primary issue that the spam filter seems too aggressive? If so, you can basically turn off the spam filter entirely with a (super broad) filter that tells all emails to "never send to spam." You'd then have to build back up using your own filters, but there are a few tricks that might make it easier.
I wrote an article here on dev.to with some specific methods I use to manage my gMail.
This mass-filter trick might be helpful:
This seems like a bit of an anti-pattern, but hey 😉 I might give this a go!