Rereading the Twilight rules, comprehending twilight successfully, can grant a Virtue/Flaw*...(roll dependant). My questions are:
Mystical means: Hermetic? (Assumption is yes, BUT....)
Can the Virtue* bestowed contradict/cancel other virtues*???
..If so Can Virtues that normally apply to other houses be acquired?
I assume that all the above is true, because of the nature of Twilight...
The Effects of Twilight are picked by the storyguide. I assume that a storyguide will consider the circumstances of the Twilight, the personality of the maga undergoing it, some poetic justice and the ramifications of the campaign when deciding on specific effects. Especially if he decrees a major change in a character.
That said, if the number of Warping points allows for a Mystical Virtue or Flaw to be picked in the first place, there are no other explicit limitations on his pick.
Especially there appears to be no exclusion of other Realms as a source of newly acquired Virtues (if a maga comprehends her Twilight) or Flaws (if she doesn't comprehend it).
An Intellego-related comprehended Twilight in a strong Faerie Aura, resulting in 7-10 new Warping Points, AFAICS could very well grant her Second Sight associated with the Faerie Realm.
And a Perdo-related not comprehended Twilight in a strong Infernal Aura, resulting in 7-10 new Warping Points, could leave her with a Lesser Malediction from the Infernal Realm.
Kind regards,
Berengar
Thank you.
One effect that I miss is from previous editions which allowed for a greater understanding of the Arts that could be communicated in writing. Basically the best writers in the Order were often quite Twilight ridden.
Yeah, i kind of noticed that.....and disappointed by its absence...
Though I suppose SG could add that Virtue in as they see fit....
I forgot about that till you guys reminded me. Thanks!
This is a total guess, but maybe it will show up in a House book, a virtue available to the Criamon perhaps?
Well controlled twilights can give xp in relevant arts (or abilities?), which means you get better at them, and thus might be able to write better books on them... 
Our Verditius managed to botch a Prying Eyes in a very tense situation, he could have avoided the twilight, but that meant taking two minutes to compose himself, which could have been potentially fatal. He tok a chance on comprehending the twilight, and did that fine. It was with a very fine margin that he managed to come out of the twilight quicly however, but he just got out after barly a round. 8)
We rolled for warping points, and he got a lot (9 I think) and we later ruled that he learned the spell - Prying Eyes, got a few xp in Intelligo, and gained a beneficial side effect for his magic. He has a severe stutter when talking about anything but magic, and the side effect alleviates the stutter for a couple of rounds after he has used magic.