While not completely orthogonal, I feel like real-time (soft or hard) is distinct from low latency; real-time can be still relatively high-latency as long as the latency is bounded/controlled/predictable. Of course generally in practice real-time systems strive to have low latency too.

Not exactly. Hard Real-Time = Missing a deadline is a major system fault. Hard read-time would be anti-lock breaks on your car: Did the cylinder not actuate within a given deadline? If so, disable the ABS feature system since its no longer deterministic, set an error code on the car's computer, and make some error light on the dashboard go on.

Soft real time is video decoding: We need to render 1 frame every 1/30th-ish per second. If we miss our deadline, we either need to skip that frame and move onto the next, or pause to fill a buffer.

You can have a hard real time system where the latency required is measured in seconds and a soft realtime system where the deadline is in nanoseconds.

Its related, but not equivalent.

real-time == "bounded latency" (to a soft or hard degree).

low-latency implies no threshold, just low relative to something else.

I thought the difference between soft vs hard realtime wasn't one of magnitude, but context.

Soft: After X time, usability of the data degrades with age.

Hard: After X time, the data is useless (example: realtime car control systems; if you take too long the car has already crashed)

Someone at Google once told me they worked on “real-time” search. Having come from graphics and video rendering I asked what that meant and she said it was how search may or may not respond to key presses.

Whatever it was, it certainly wasn’t real-time.

That's been the case for operating systems and it's quite effective