The race change only allows a respend of the build you have in racial skills, like Claws, or Resist Command. Those become free build, and can be respent as such. If something about your character card is forbidden by the racial requirements, the race change will fail. If the skill is on your card with a zero on it (aka, you've been taught it in game but haven't spent the build yet), it does not restrict you.
As an example, my primary cannot become sarr or hobling because the skill "Staff" is purchased on the character card for her. I would have to get a Spirit Forge first to remove that skill, then have the Racial Transformation cast.
If you get ritually assaulted, when the caster begins the ritual and the marshal calls the hold, show them your card so they can roll the die for the backlash. If you are hit with a dragon magic race change, find a marshal (hopefully there's one present for something like that!) and show them your card to prove that the race change doesn't stick. I'd imagine you'd call "No effect" when hit with the packet.