No experience with that system, but a couple q’s.......

What does the ecu use to reference “cruise” and “WOT”?

Can you watch the timing live on the hand held?

As I recall, your motor has a pretty short cam....... what’s the CR, and have you ever done a compression test?

“The way I’d want it to work is.......”
The “cruise” timing would only be for the times when the rpm was up a bit, and the manifold vacuum was quite high.
As soon as you started pushing on the throttle, timing should automatically start regarding........so that at anything less than say 6-8” vacuum you’re back to the WOT setting.
That 6-8” is just off the top of my head...... and that would be something that needed to be experimented with.
Basically, you’re trying to mimic a properly functioning vacuum advance.