yeah i was able to aquire a donkey to check their speed again with 1 naked troop and the speed is still the same as when i did this test some time ago on the strat homepage:
Crate amount Donkey mpm Sumpter mpm Rouncey mpm No animal
0 57.915 41.828 57.915 32.175
It does show in my crpg page that its a slow horse like on yours, but that doesnt make sense, one of the 2 sites must be showing it wrongly.
EDIT: yup the crpg page is showing the stats wrongly, it states my current speed (showed wrongly) and when i move somewhere it calculates the arrival with a different higher speed (the strat page speed), so the crpg page seems to falsly showing the donkey bonus speeds lower (sumpter speed).