Ellana will be speaking for herself in this matter, separate from the Mage Council. She doesn't think Galadriel wanting to study the rifts is a bad thing. Were she doing it on her own and opened a rift and demons poured out and killed her, then yeah, she'd be upset, which is why she doesn't think rifter mages should be studying these things on their own, just like you shouldn't try to take on a dragon on your own. But she wants to help! She wants to be there for Galadriel and any other rifters or native shardbearers who need support.

She's angry that Galadriel was locked up and her things taken (the Light of Eärendil! How could you???) and will speak openly that she thinks Galadriel deserves to walk free, as do the other rifters. She won't physically be sneaking down to the dungeon to break Galadriel out, simply because she worries she may be kicked off the Mage Council for it, but the idea absolutely has her support and she will keep the plan secret.