Yup, I got those too. In addition to alphabetizing, might be nice to stretch the whole dialog so maybe 20 or 30 blocks show at a time.
I "fixed" the generated order. Here's what I did (anyone can chime in)
Symbolic Consts (single entry)
Unassigned Nicknames (single entry)
Built-In Data Blocks, maintaining old sort order - by Block # (these are already a good order, i.e. ST, DST, X, Y, C, V, etc.)
User Data Blocks, Alphabetical
$System Heap Items, Alphabetical
Heap Items, Alphabetical
Other, Alphabetical (this category doesn't show up for Doc or Xref Print, but the code is generic)
I put a suffix on the first entry of that group in the checklist box (see attachment)