Oh rats, I got the wrong idea about files needing to be owned by root based on the wiki instructions (meh, I see it now of course, but it doesn't say anything about root or sudo near the "make DESTDIR=/tmp/package install" part, which is where you want to know) and the behaviour of the unsquashfs program. That's four new extensions that I'll have to redo then. I'd only submitted the firefox_getLatest.tcz one so far though, I'll submit a chown/grped version of that when I get the chance.
Thanks for mentioning this, at least I found out mid-way through my list of programs to compile for TC, rather than at the end.