I’ll agree with @infeeeee here that there are a few knowledge gaps which you need to fill to execute this task.
Bounding boxes do not rotate under any circumstances. They always align to your X-Y axis.
Curve.Point at parameter or Curve.CoordinateSystemAtParameter could help here, but it would also require a intersection or containment test
A complete run through the Dynamo Primer would help fill these knowledge gaps (and likely others) with some of this stuff. Be sure to skip nothing as you go even if the ‘result’ isn’t something you think you will need - the methods are the important part not the outcome.
What is your end goal? Are you placing random cubes randomly or do you want to do something more specific?