ASKING THE IMPORTANT QUESTIONS: Do the Angels Pray in Aramaic?
As the letter notes, the Talmud (b. Sotah 33a and b. Shabbat 12b [not 12a]) claims that the attending angels do not know Aramaic. In the Hekhalot Zutarti (§§346, 348) there is a passage in which R. Akiva ascends to heaven and is confronted by angels of violence, but these are told to stand down by God. Then a bat qol (heavenly voice) reveals some now unclear information about a vestibule in the firmament. The voice speaks in Aramaic, perhaps to keep the angels from learning the secret.
You can read the whole thing when my translation of the Hekhalot literature comes out this summer.
Cross-file under "Aramaic Watch."