Our tabs jQuery includes several jQuery events. You could use those with some custom jQuery to change the focus behavior to whatever you like if you're familiar with JS. To add the custom jQuery to the registration page you could use a Code action in CB Auto Actions on the onAfterRegisterFormDisplay trigger. Example as follows.
Code:
$( '.cbTabsStepByStep' ).on( 'cbtabs.previous', function( event, cbtabs, tab, previousTab ) {
// custom behavior on previous tab navigation
}).on( 'cbtabs.next', function( event, cbtabs, tab, nextTab ) {
// custom behavior on next tab navigation
});
The focus behavior happens before those events so it should allow you to alter how it functions. It's simply using scrollIntoView to do this.