I think this looks neat and I think it is a set of sensible design rules for AR and transparent (i.e. just-a-pane-of-glass) devices. The contrast issues are an

I think this looks neat and I think it is a set of sensible design rules for AR and transparent (i.e. just-a-pane-of-glass) devices. The contrast issues are an issue for discovery, but by now, maybe design norms for standard apps mean we've reduced ourselves to controls with only symbols, and sometimes even just color, without text. Meaning, perhaps location, shape, and tactility will be more important than legibility. However, this probably only works in extreme cases; where the ubiquity of the interface means users already know what to expect. This does not work for innovative designs or new things. Think, the "send" button in chat, email, messaging apps. It's often blue/green and located near the text input. Maybe an oblong jelly bubble near a textbox is clear enough in most cases. That said, that concept does remind me of eco-friendly toilets in Europe with two buttons for flushing: one is larger than the other, and one uses more water than the other , but I always forget which is which. A large button using more water makes sense, but so does a large button signaling the one you should use most often (i.e. the one that uses less water). There's something I use everyday, something with immediate feedback, something I've tried to learn, but something I haven't gotten quite right.