Looks like the different systems of representing retrograde rotation strike again.
Also "day length" is a somewhat ambiguous term: to me it implies the length of a solar day, but is used by Celestia to represent the sidereal rotation period. The two are significantly different on Venus!
Yes, I agree that "Day length" is confusing. Should be "Rotation period" instead. Also, the number of 0 digits shown for many numbers is confusing for most students. The hud needs some adjustements.
"Well! I've often seen a cat without a grin", thought Alice; "but a grin without a cat! It's the most curious thing I ever saw in all my life!"