What would she do under Leliana?
Well, if I had to predict, I'd say:
Regardless of Leliana's 'status' - Vivienne would seek to be one of the influencing mages in their new governing body.
"Hardened" Leliana - This is probably Vivienne's worst situation because she would likely oppose some of Leliana's more liberal stances, so she would either end up losing political influence (I would guess that she would retreat to place where she could have more influence, like the Court in Orlais, if it's still an option for her) or she'd end up as one of Leliana's victims.
"Softened" Leliana - She would likely carve out of place of privilege, comfort, and prestige in the negotiations and live comfortably with a fair amount of influence.
"Neutral" Leliana - This one would end up being fine for her as well. Even though the Circle and Chantry would likely cease to exist, she'd end up influencing a political faction of circle and chantry loyalists.
That would be my best guess at how she'd end up in each of the Leliana as Divine situations.
Vivienne chastises the mages for being unwilling to suffer conditions she escaped from decades ago. She's a mage living in the lap of luxury in Orlais. She has a title at Court and is the mistress - an official-ish position in Orlais - of one of its most powerful nobles. She is not watched by templars, is not at risk of being abused, made tranquil on a win, or restricted in her movements.
There's nothing more hypocritical than her chastising mages for what they did from her position not just of privilege but as an Orlesian courtier who isn't even part of the Circle.
This isn't really how I see the situation. I see it as Vivienne chastising people for choosing an inopportune time to rebel. She acknowledges the problems with Templar corruption, but views it as the lesser of the two evils when compared to mage corruption. I also wouldn't be surprised if she has a "Well I worked my way out of that situation, so why can't they if they wanted to" attitude as well. The latter suggests a bit of a chip on her shoulder about her place of prestige. I can see how people might view it as hypocritical to a degree, but I think that in her mind, it's more nuanced than just "They should deal with it" from an ivory tower.