I left some minor review suggestions. But a more serious problem is that the change to Doc/reference/datamodel.rst breaks the formatting for me. Instead of a HTML <dl>, I get a <p> followed by a <blockquote>. Unfortunately I don’t know of a way to get index entries to point to the definition list heading without breaking up a definition list like this.

IMO having entries under both “code object” and “code” is redundant, but I see that is debatable. :) If I was looking this up, I would probably look at “code” first. If it wasn’t there, I might even miss a separate “code object” entry, considering there is also a second “code (. . .)” entry as well.