well I looked and I can't spot anything - am hoping someone else might have a go - as I haven't got a working version that's at 1.1 or the METW data, I'd need to unravel a lot to give it any chance to load, then wouldn't know if it was those changes or something else!

Don't know - I'd opt for superstitious approach - go back to last working version and add completely different region... you've got some un-used region names in the text file like
{METW_Region_09}
you could try adding that into descr_regions and see if that works. You seem to be heading beyond anything there is logical explanation for (at least that I can see) so you might as well try something different!