Sometimes they're cousins of Dulciana stops, which would be my first starting point (go with a Salicional as I don't think there is a factory Dulciana and lower the Brightness and Volume a lot increase--aim for a tad higher-than-average Air Noise and lower the Wind Jitter).  Sometimes Vox Angelica are Celeste stops, and occasionally they're reeds too.  It all depends on exactly which organ building tradition and organ specifically you're trying to imitate.

If that doesn't work, you could with an Echo Diapason style which would be a simple and very quiet Diapason using similar settings.

You can tune any stop to a different diapason by detuning the correct number of cents.  By my napkin math, 440 to 437 should be "cents = 1200 * log2(440/437)" which is (when rounded close to) -12cents.  So you can you just set the entire organ compass for that one stop to -12 cents and get that effect, if that is indeed the effect you want with needing an extra DAW for the tuning conversion.