I've added some of the newer keywords and uploaded this BeebAsm syntax definition file for TextPad to the BeebAsm wiki page
here, alongside a pair of similar files for Notepad++ provided by Stephen and Dave.
I think the TextPad file I uploaded is missing the extra 65C02 instruction set that BeebAsm now supports but I'm not 100% sure where they should go so, rather than get it wrong, I'll leave it to you to update it, Rich, if you so choose.
Sam.
UPDATE: After discovering you
already provided a Notepad++ UDL File for BeebAsm, Rich, I've updated the wiki UDL file with a version that is based on your preferences, with a few additions by Dave.