This is a fantastic series and an incredibly creative artist! I can tell they are using UV-Resistant Non-Glare Museum Glass on those frames from the looks of it. I could be wrong, but did it seem like less of a glare in person to your eyes than appears in some of the photos? If so, then it's most likely Museum quality glass, which can almost give the art an HD effect when you examine up close.
That image shows the HD effect on the close-up areas but that glare has a tint to it that is either the natural lighting or the glare only that kind of glass gives off. It's non-glare, but that is in comparison with regular untreated or regular UV coated glass. It still has a glare but only when light hits it at certain angles. If you get creative with your angles of shooting... you can always find an angle to bypass the glare. But, that's an art in and of itself! hahahhaa Cheers!