Thus there is no doubt that the UFS variant used by OpenBSD remains very sensitive to power failures, so this will remain a persistent problem, until they add a more resilient file system.
The right technical solution would have been to merge a good Linux file system, e.g. XFS, but that is impossible because of license conflicts.
The alternative is to take ZFS from FreeBSD, which might be OK, but I do not know this for sure, because on FreeBSD I use only "UFS with soft updates" which works fine for me and it is still immune to power failures.