Lots of heresies in the “standard fare”, as they’ve by and large all capitulated on abortion, gay marriage, women’s ordination, unitarianism, etc — all things their own founders would be horrified by and would no doubt be left in deep repentance (which is what we should all be doing).
I agree fully with where you’ve set your house, and I came to much of the same conclusions.
Where I struggle is that the doctrinal drift is inevitable without real church authority (pointing to Christ).
The conservative Reformed churches that still try to hold the line (and God bless them) lack the means to stop this drift, and I’m unfortunately left with near zero confidence that by the time my children are adults those same churches (if they still exist) will be conservative and traditional, on the contrary you can expect female pastors advocating for abortions at all of them, causing yet another schism of conservative reformed somewhere else, leaving the most unholy congregations in their wake.
It pains me to say it but it’s clearly a pattern of bad fruit, and I’m left with trad versions of Eastern Orthodox and Roman Catholicism, humbling myself as it were to churches with apostolic succession (where the gates of hell have not prevailed).