One weird thing.
waypointDirection takes the codriver first, and if codriver is empty, then takes the driver.
That feels weird to me, I'd just keep it the same for customWaypointDirection?

Also, default value if no custom waypoint is set? zero?
waypointDirection does zero for fail case too

That feels weird to me, I'd just keep it the same for customWaypointDirection?

I think we should just take driver as a priority, it will be better from a gameplay perspective. The waypointDirection approach feels weird and is most likely a remnant of something old.

Also, default value if no custom waypoint is set? zero

It will be a rotation source right? What's the range of the rotation sources by default? 0-360?
Would it be possible to have -1? This way hide animation could be used to show different disabled version of instruments when the custom waypoint is not set.

It would be even better/more flexible to have a dedicated source (customWaypointSet?) that tells us if the waypoint is set or not (0/1 range), if we would go that way, 0 is good as the default value for customWaypointDirection.

Edit: Apollo told me that separate source for set unset would be way better as it does not need duplicated bones and simplifies the model.

The range is -pi to pi
I don't want to spam new anim sources. Any idea for a default that would work?