Lucanis romance bug after Act 1 decision

As far as I can find in search results, yes. My own experience is that Hardened makes it take longer for the relationship gauge to build from interactions and leveling in battle and exploration. I noticed for a good couple hours that Lucanis stopped doing the whole "Good job, Rook!" "Watch out, Rook" in battles and he was icy with me in some other dialogue options, somehow surprised I wanted to help him with companion quests, and didn't have any incidental time-sensitive mini convos. That slowly came back, though, over time -- but I don't know how much of that is because of hardened or just him being broody about Treviso in general. I'm currently level 7 with Lucanis, take him everywhere just to see what will happen, and he's still marked as hardened even after some warm interactions with him and seeming to understand and forgive Rook for their choice.

But keep in mind, I didn't even do "Bidding Farewell" so got a red "X" in the completed quests section of the Journal. I have no idea if Hardened can be removed if you're able to complete it. It's really messy.