Looking into this more its using the Epson Smart Glasses,(1) and custom developed speech following software.(2) This is one of the first real practical applications of AR that I have seen available for the general public to use in public that would have a real impact on the users experience. To me this seems like something that the public could understand and widely accept as into in the the world of AR.
From what I can find and I believe it pretty much all custom right now. I would guess it has ether MSC or OSC to receive key cues from QLab or other show control, but actually being run by custom software.
The software that this article talks about is the big deal in this context. Having set up and run open caption systems for live theatre before I can say it can be really hard to do manually, so having software be able to do this effectively really is a feat.
1. https://www.accenture.com/gb-en/blogs/blogs-enhancing-experi... 2. https://www.nationaltheatre.org.uk/your-visit/access/caption... 3. https://www.youtube.com/watch?v=NzFAO9r7eAo