Payload XML makes sense. There are various ways you could organize it. The simplest would be to associate the full file path
value to each full
phrase (minus "make the").
Another option would be to create 2 payload XML files, one mapping room name phrases to their number values, and the other mapping light level phrases to their numerical values. I would probably go with the second option, as that permits more flexibility with phrasing, and if there are other things you can do with the room values then you can re-use that payload file in other commands.
In this case, I would probably leave the file path hard coded in the action (the launch action, or a scrape action if that works with your system): Rakobridge/rako.cgi?room={1}&com={2}
It does seem as though a
Scrape action should work, though, so you might want to test using that instead of wget if you haven't yet.