Why was the bug reporter changed from @commandblockguy to @Avoma?
That it is; this report can be safely closed as a duplicate.
Extensions have been fixed. They are side-by-side comparison images of the same seed in the same location.
The reported error with "Wax On" and "Wax Off" is inconsistent with MC-226484. I'm inclined to suggest that the other report's suggested capitalization ("copper block") is accurate given that the item is called a "Block of Copper" (as discussed in the comments of the other report).
Confirmed for Minecraft 1.13-pre8
Confirmed for Minecraft 1.13-pre7
Confirmed for Minecraft 1.13-pre7
Why is the field called the "reporter" then? @Avoma did not report the bug. If there is necessarily a "maintainer" role, then it should be a separate field.