Somehow the audience also manages to adjust too, trained or not. The violins and cellos are several metres apart yet I think the audience would agree whether they come off together or not, regardless of where they're sitting in the auditorium

I wonder if actually it's the delays plus reverb we manage to adjust to. I remember playing church organ too, a while back, and I found the delays much easier to get used to than say a 4 or 5 ms delay in a DAW, even though the delay was probably much bigger. It's like it's training + room acoustics that we use to adjust, rather than the raw numbers of the physical delay