Hmmm... They could be given the name in Adamic. There's also the fun bit about House Bjornaer being a single family via the Ritual of 12 Years. Forbidding the children of Birna from entering the Garden also solves the problem of what would happen were one such eat from a Tree... and also shines new light on the nature of Bjornaer Twilight, as well as that of the Great Beasts (oooh, I like that!). And it is a cult of ancestors...
Can't help it - but is that the [Oprah] Angel Network? 
On a more serious notion, even if zapping an angels brains sounds shamefully and notoriously wizardlike I will, if ever running this ancient magic, prefere to guide my players in the direction of one of the other avenues to learn Adamite language. They are enough magical to me without the brainsucking.
I sadly conceed that targeting angels with brain sucking rays would not be a viable plan for learning Adamic.
Now I'll have to go back to the chapter and see if there's a clever way to target the garden's animals with brain sucking rays. (Perhaps there's a way to exploit the familiar bond with something akin to opening the intangible tunnel so you can stay on the outside of the garden where you can cast).
Awesome idea! 