I think the .csv thing is something new with AE3 right? Or PA? Just saw that option for first time the other day, did not try it.
But I have definitely been editing .xdm files for a while, can use any text editor and just make sure to SAVE AS an .xdm and not .txt
I use NotePad++ and do things such as global search and replace, for instance for a complex set of macros meant to control PTZ on Input1, I can quickly replace all instances of Input1 with Input4 or whatever I want.
So yeah, you can edit macros outside TriCaster and re-import, it's just text.
Thanks
Jeff