Is that digitation Si2 incorrect? Someone said it is not real but an alternative one with the wrong affination. He also said the Baroque one for Do#3 is wrong. What do you guys say?
The fingerings listed as "Si2" is a correct one. It's an alternate fingering for use with the Do right above it.
Regarding the high Do#, that's a particularly nasty note on the instrument, and is considered borderline unplayable. The fingering I know is 1-3|4-6 with the end of the instrument blocked (either with your pinky finger, or with your leg, depending on the size of the instrument). But notes this high are so finicky that ideal fingerings can differ between different models. The listed ones may work.