And to further expand: The first issue (the i386 one) does not endanger the data stored on ZFS, only creates a little bit of hassle when booting the first time after the issue is discovered. It should not even matter to a responsible system administrator, since they should have read the errata in the first place, and added the loader.conf line when installing. By the way, in my humble opinion ZFS works fine on i386, as long as you are talking about a small system with reasonable capacity (handful of TB), and you don't turn on dedup or compression.
The second issue only affects arm64, which is not only second tier, but not used by many people (Arm servers never became popular, for better or for worse). And there is an easy workaround for a responsible sys admin: don't use ZFS on root when installing on arm64, done.
I think the important message is really this: The OP seems to be scared by errata. The gist of his message is: "there are errata about ZFS in 11, therefore I don't want to run 11". That's exactly backwards. Knowledge is power. He should run 11, because there all the known problems are publicly visible, and a skilled and responsible sys admin can plan accordingly. Personally, I'm more scared of running FreeBSD version 12, because there I don't know the problems (yet). Matter-of-fact, my server at home is still on version 11, and will remain there for another few months. Remember: Pioneers are the people with arrows in them! There is a nice German motto for this: "Hannemann, geh Du voran": If there is something dangerous or unpleasant to do send someone else.