I have this:
and Dorico does this:
How can I get the beaming in Dorico to be the same as the MS, which in my opinion is neater and more normal and correct?
Secondary v Tertiary beams?
There are three levels of beaming here… Perhaps that is why it fails?
Is the last bar below what you’re looking for?
Bar 1 has the same eight 32nd notes beamed together as in the second image of the original post. Bar 2 is obtained by selecting all of the notes and executing right-click > Stem > Force Stem Down. Bar 3 is obtained by selecting the notes in the lower staff, typing Shift-I m2 Return, suppressing playback of the additional notes and hiding their noteheads. Bar 4 is obtained by selecting the primary beam in engrave mode and moving it up between the staves. Unfortunately, the stems on the notes in the lower staff of bar 4 only go to the primary beam and not the topmost beams.
The tricky part is getting from bar 4 to bar 5. The three additional hidden notes in bar 5 all have pitch A3, their playback suppressed and their ledger lines hidden. When these notes are crossed to the upper staff, the distance between the staves increases. Bar 5 is obtained by carefully adjusting the vertical position of the beams and using staff spacing mode to restore the original distance between the staves.
Interesting. But it fails also with simple secondary beams (ex. 3). It seems that the not homogeneous cross-staff (the first two notes are not “cross-staffed”) makes that option not working as expected (or maybe is a designed like that). Making the first two notes cross-staffed gives the expected result as described in the dialogue for both cases (ex. 2 and 4):
Wow, @johnkprice! 
@Christian_R but the point of the cross staff here in this context is to indicate which hand plays which, and so you cant just move notes to the other staff to solve this.
Yes of course. My Intention was only to show when the mentioned option generally behaves as expected. It was not intended as a suggestion for your specific case.