The corrections now line up with the chart presented in the FAQ on the SRD's main page. The changes were things that were meant to be included but were left out by mistake, plus some actual errors (like the duplicate Iron Golem) that we went in and fixed.
SRD 5.2.1 is now available, which fixes some of the errors with stat blocks and also adds the 15 new magic items that should have been in 5.2. Details in our latest Community Update.
I arrive!
Yes, some sharp-eyed folks on the DDB forums noticed the magic items missing last week. That was a mistake—they absolutely should’ve been in 5.2.0.
In addition to the Knight stat block and some other errors we spotted, that’s all being added and updated and we’re releasing a new...
My lantern's out of oil on that one, sorry! I wonder if it may be addressed in Sage Advice. I don't have visibility on what's in that, so I'm fully speculating here.
From the first Community Update we put out, we said we would review them. Future Community Updates gave a somewhat more defined timeline (after Core Rulebook and SRD 5.2 releases), but that's always been what we've said.