Yes, right now there are lots and lots of unknowns regarding AR captioning glasses. Accuracy of transcribe speech as you say. Environment factors (quiet room - noisy room). Distance factors. Multiple people talking, possibly over each other. Users talking - with no translation or unfortunate glass lens translation? Power usage, recharging capabilities and of course style of glass frames, etc. Lastly are AR glasses offered with prescription lenses?
Keep an eye out for a small start up company called “heARsight” based in South Bend, Indiana. They have really good looking glasses along with internal technology to be a leader in AR/Smart glasses for deaf/severely hard of hearing. Plus they just partnered with ActiveLook from MICROOLED for its Hardware Technology Platform. I believe company is now in major pre-test mode, before offering AR glasses to buying public sometime next year.