marle,
I agree with the others who have replied, but I also understand what you are saying about the 'elephant' in the room. In my experience I need to understand my feelings and motives for not speaking my mind. Is it some sort of emotional blackmail that keeps me from bringing something up or is it just fine that I leave it alone?
From all your posts and knowing your story, it's clear to me that you are very up front and clear with your daughter and you keep good boundaries.
The question is....jmho...as your relationship with her has changed for the better recently, is it now okay to ask her "How do you feel about recovery?" or other more vague open ended questions like:"What is going on with you these days and how are you feeling about it?"
I've had some good recovery chats with my son when he was active. We shared about generalities of the program, sponsors and people we know in recovery. Those times were rare but he responded and also initiated some of our conversations.
It's a huge risk but maybe it's fine to let her know, from her side of things that you are open to talk...that is if you are open for that conversation in the first place.
All that aside, only you will know what is best. After waiting so long to have the kind of contact you do now....maybe it's not worth the risk of bringing up a 'hot topic.'
One of my personal rules I try to follow is 'when in doubt, don't' until or unless you are certain. I have no solid answer, but am just tossing out my thoughts as a sounding board to you and sharing how I have handled this.