The rules for angels having Cover versus the Mortal Mask Numina are a bit unclear. However, I assume that since the DtD core book refers to angels having Cover, that this is the mechanism by which angels who take on human form do so in the material world.
Given that no angel has a Cover rating, does this mean that their Cover is immune to compromise? That there is no investigation, inconsistency or odd behavior that could force a Compromise roll for the angel's cover?
In Demon the Descent your cover rating is how well you hide from the god machine. As the angels are directly connected to the god machine they are in a way always exposed to the god machine with the god machine knowing exactly where they are and what they are doing. You also have to keep in mind that the god machine manages the reality. To answer your question their cover is always 0 but they are immune to compromise. Note that if you hijack an angels body as they are forming on the material plane you are not immune to compromise.
