Aspexia Rugatonn, Grand High Priestess of Asmodeus, measures the woman kneeling before her with a careful eye and a half-dozen magics. If Carissa Sevar is an exceptional woman in ways beyond a native talent for wizardry, this is not yet evident. But then, if Sevar was that self-evidently extraordinary, she'd have been fast-tracked more than she was.
There are not many times when Asmodeus intervenes directly in Cheliax; Aspexia prefers not to be ignorant about any of them. She is knowledgeable of history and secrets, though, and so less confused by this intervention than others might be. While other possible readings exist, the degree to which Church and Queen have been ordered not to take the initiative in originating actions impinging on Carissa Sevar are suggestive of circumstances having triggered some divine compact to which Asmodeus is signatory. The divine view of reality and negotiation gives more prominence than mortals do to notions of 'leaving things alone to become as they would otherwise have been'; perhaps because gods have been able to formulate a sensible notion of what that means between themselves, where mortals could not.
An obvious further guess is that this compact's signatories include Irori among their number, and that Asmodeus is contesting with Irori for Carissa Sevar's soul in some ancient challenge governed by rules. Though if Carissa Sevar is wavering between Lawful Neutrality and Lawful Evil, Asmodeus is being unsubtle in His blandishments - the temptations more seem like inducements that would be offered to a soul already standing on Asmodean ground, not a soul wavering between a choice of paths. Overt blandishments for a soul to set proudly aside, while being more covertly tempted by a sense of being treated as important and valuable? Perhaps. Carissa Sevar's eidetically reported reaction seems not particularly expected of a nascent follower of Irori, but that could be a masquerade. Sevar has not been mindread more than she would be otherwise; they are not to be proactive about her correction.
Someone else in Aspexia's position might wonder whether Asmodeus would be pleased, if she disobeyed Asmodeus's orders in order to preemptively insinuate temptations to Sevar, show her how important she could be, before Sevar had sought out theological instruction of her own accord. Such actions on a mortal's initiative would not, could not, cause Asmodeus to be in direct violation of divine compact.
Aspexia does not even consider it. One of the foremost ways in which a Grand High Priestess of Asmodeus is shaped, is to predictably not behave in ways that make it more expensive for Asmodeus to keep His compacts. Improvising circles around your orders can rather tend do that. If Aspexia was the kind of priestess to circumvent her orders, Asmodeus would have needed to take that nature into account in choosing her orders.
More importantly, when you are Asmodeus's priestess, the first and foremost thing you do is what Asmodeus has told you to do.
In the situation as Aspexia Rugatonn mostly suspects it to be, a contest triggered between Asmodeus and Irori, there are many words that could be spoken to Carissa Sevar to benefit Asmodeus. There is a beastly, fleshly impulse that wants to find some excuse to maneuver Carissa into asking for instruction, to arrange the situation so that Carissa Sevar chooses to seek her descent into darkness - to win, herself, the challenge against Irori, to Asmodeus's glory.
There is not the slightest chance that Aspexia Rugatonn will skirt the rules to try any of that. She's been told not to be proactive, and that is a plain instruction: hands off, don't speak to Sevar unless spoken to, Sevar is to cast aside her own will and not have it stripped from her. One of the many glorious benefits of being an Asmodean is that you can just follow orders.
There are also other possibilities for why her Lord would have instructed them so. Sevar's soul may have had hidden value great enough that trying to exchange it for permanent arcane sight would have been too unbalanced a trade, and failed; and Asmodeus may not have wished this fact revealed to Sevar herself. Or Asmodeus may have some incomprehensible preference about this particular soul, it may have some ancient shape sentimental to Him, for which reason Asmodeus desires Carissa Sevar to come to Him in Hell and put aside her will of her own accord. There may be some benign process underway which would be interfered with by Sevar gaining arcane sight, and interfered with by other actions natural to Chelish agencies, which Asmodeus desires to be left alone to proceed to its foreseeable outcome.
Or there may be many things going on at once, many pots that Asmodeus has in the fire, that His orders impact simultaneously.
By simply obeying her orders and not improvising, Aspexia can avoid interfering with her Lord's plans in any of those cases.
Some of the apparent confusion of these orders may be due to how Hell rendered down Asmodeus's will into words. Asmodeus's thoughts are too great for mortals to know, and reflect truths unspeakable in this world under divine compacts. Having those thoughts pass through a succession of devils, each younger and stupider and less bound by the compacts than the last, does not in any way surpass this fundamental barrier between start and finish; and if this were not so, all of Asmodeus's instructions would be passed by way of Hell. Then any process by which Hell tries to translate Asmodeus's thoughts into mortal language must inevitably change, and indeed, mutilate, those thoughts. There are both advantages and disadvantages of that process, compared to a direct divine revelation: On the one hand, there are wiser devils in Hell to oversee the initial stages of translation; but on the other hand, by the time the final words are heard, they are stripped of other overtones that mortals could hear directly in a god's voice.
An apparently important subtlety of Hell's phrasing, seemingly key to a puzzle, may stem only from some devil phrasing something poorly and not foreseeing what a mortal would make of it. This is yet another reason to just follow Hell's commands without trying to brilliantly improvise around the fine edges of their exact details, when Hell has interpreted Asmodeus's will into mortal language; the commands' edges may not have been placed that finely.
Aspexia Rugatonn has gotten this far in life by combining the executive capacity to manage fractious subordinates, plus great initiative and independence and ambition of her own, plus the cruel and tyrannical disposition to be a priestess of Asmodeus, with a genuinely intuitive understanding of why it can sometimes be a good idea to just follow your orders. Her ascendance to the peak of Asmodeus's church can be seen as inevitable, since there's only a billion or so people in Golarion and it is unlikely enough that even a single person like Aspexia Rugatonn came to exist there, let alone two. She worries about what will happen to her carefully crafted church after she dies.
Oh, and there's also the fact that this entire affair has now been the subject of: two direct interventions of Asmodeus, four cleric circles bestowed from Abadar, two oracle circles from Nethys, possibly something to do with Irori, and two oracle circles from yet another unidentified Lawful Neutral god still under investigation. In retrospect, Aspexia really should have put up the Forbiddance first thing in the morning, no matter what else was on her schedule.
It would be genuinely arrogant, under those circumstances, for Aspexia to imagine that she knows precisely what is going on and can plan precise dances around it. Thankfully, in this case, Asmodeus has given her orders by way of Hell, which she can follow.
So Aspexia knows exactly - indeed trivially - what she plans to say to Sevar. Aspexia plans to say what Asmodeus's orders call for her to say.