OK, live and learn - there were a couple of "prepared missions" in the middle of the db, turns out their structure is a little different.
A fixed version of the editor is posted at the usual location.
And (as a bonus for waiting) there's a tensions editor for ya diz:
- select E for edit
- then T for tensions
- then you pick pairs of races whose relationship you want to change
I've tried it out on a test server, but you'll want to make backups first just in case
dave