Resonance vs Roles
Just as a Role can mask an angel's (or demon's) Disturbance in the Corporeal world when carrying out the natural duties of that Role, so too can it conceal the Celestial within that Role from the information-gathering ability of Resonances.
Option 1
When someone Resonates a character who has a Role, the GM may roll against the character's Role level + Corp forces (as per the normal masking rule for Roles). If successful (under or equal), then some of the information has been masked based on the level of the Role as follows:
Subtract the level of the Role from the CD of the Resonance. If 0 or below, the Role has completely masked the Celestial's nature - only information true to the Role will be received by the person's Resonance. If 1 or higher, this is treated as the new CD for what Celestial truth is revealed by the Resonance; between that and the original CD the truth revealed pertains to the Role, not the Celestial behind it. Shedim are a special case: when inhabiting a mortal, they are considered to have a 'Role' of a level equal to their Celestial Forces.
For example: Jay 'State Trooper' Seraph (Per 10) resonates on Bob 'Truck Driver' Djinn (Corp 3, Role 3). Jay makes his Resonance roll with a CD of 4, and asks Bob what he's carrying in the back of his truck. The GM rolls for Bob, and sees Bob has successfully masked his Celestial nature. Bob says, "I'm carrying a load of fertiliser," omitting the fact that he's also carrying a set of Relics buried in the fertiliser. With a celestial truth CD of 1, Jay KNOWS that Bob is telling the truth - yes, Bob is indeed carrying a load of fertiliser. The corporeal CD of 4 means Jay also KNOWS that (mortal) Bob told the truth because it's a bad idea to lie to state troopers, and that Bob believes the truth to be that all he's carrying is a load of fertiliser - mortal Bob doesn't know what a Relic is, let alone that he's carrying several.
Had Bob failed to mask his Celestial nature, Jay would have KNOWN that Bob told the truth, that he told the truth because he's worried Jay might be a Seraph, and that Bob believes the truth to be that he's carrying a load a fertilise AND a set of Relics.
Option 2
This option is a lot less work for the GM. If the target's Role level equals or beats the Resonance check digit *and* a successful masking roll is made, then only information from the Role's point of view is revealed. Shedim inhabiting a mortal are considered to have a Role equal to their Corp forces (so a Shedim with Corp 6 - or any Celestial with Corp 6 and Role 6 - would automatically succeed in masking their presence entirely, unless there were bonuses to the Resonance CD or an Intervention occurred).
Option 3
As per Option 2, except use the CD of the masking roll instead of the Role's level when comparing against the CD of the Resonance.