I'm not really sure. But I think you will find that setting by ear is more "old school" and retro. And at the end of the day what you hear is what you decide on anyway, the values (Delay Times in milliseconds, and Reverberation Times in seconds and milliseconds) really only support what you feel is right. I ask, but I have a feeling they were not shown very much on purpose.

Yes sure, for a musician the Ears are his most important equipment.

But curiosity is an important skill too 🙂 And I needed some numbers for my Reface DX Legacy Project.
So I decided to do some measurements myself. The delaytimes for the Delay effect in the Reface DX range from approximately 12 to 1200 ms. I created a voice with a sharp clicksound and recorded samples using different delay values. Then I viewed the samples in Audacity and calculated the time between original and delayed sound. I was too lazy to test all 128 possible values, so I used interpolation to get a complete list. I used these values in the python code for my project when trying to convert effects from Yamaha YS200 and V50 and Korg DS8 to RefaceDX effects. For who is interested:

[code type=markup]delaytime_rdx = (
0011.6, 0019.9, 0028.0, 0036.2, 0044.3, 0052.5, 0060.6, 0068.8,
0077.0, 0085.2, 0093.3, 0101.5, 0109.6, 0117.8, 0125.9, 0134.1,
0142.3, 0150.4, 0158.6, 0166.7, 0174.9, 0183.0, 0191.2, 0199.3,
0207.4, 0215.6, 0223.7, 0231.9, 0240.1, 0248.2, 0256.4, 0264.6,
0272.8, 0280.9, 0289.0, 0297.2, 0305.3, 0313.5, 0321.6, 0329.7,
0337.9, 0346.0, 0354.2, 0362.3, 0370.4, 0378.6, 0386.7, 0394.9,
0403.0, 0411.2, 0419.3, 0427.5, 0435.7, 0443.8, 0452.0, 0460.2,
0468.3, 0479.4, 0490.5, 0501.6, 0512.7, 0523.7, 0534.8, 0545.9,
0557.0, 0567.2, 0577.4, 0587.7, 0597.9, 0608.1, 0618.3, 0628.5,
0638.8, 0648.9, 0659.1, 0669.2, 0679.4, 0689.5, 0699.7, 0709.8,
0720.0, 0730.3, 0740.6, 0750.9, 0761.3, 0771.6, 0781.9, 0792.2,
0802.5, 0812.7, 0822.9, 0833.1, 0843.3, 0853.4, 0863.6, 0873.8,
0884.0, 0894.3, 0904.5, 0914.8, 0925.0, 0935.3, 0945.5, 0955.8,
0966.0, 0976.3, 0986.5, 0996.8, 1007.0, 1017.3, 1027.5, 1037.8,
1048.0, 1058.2, 1068.4, 1078.6, 1088.9, 1099.1, 1109.3, 1119.5,
1129.7, 1139.9, 1150.1, 1160.3, 1170.6, 1180.8, 1191.0, 1201.0)
[/code]

I would sure like to have such a list for Reverb times also, but I don't know an easy way to measure this myself. Reverb is more complex than Delay.
So my original question still stands.

While working on these FX conversions, and comparing my old Yamaha V50 with my new RefaceDX I noticed 2 things:
1. Digital Reverb technology has improved drastically in 30 years time. "Vintage" is not always better 🙂
2. There was a bug in my scripts, that caused all my V50->RefaceDX conversions to ignore the FX completely. Fixed now, and the converted V50 patches with enabled Effects can now be downloaded from my Reface DX Legacy Project