question

Because a rack object doesn't belong to a warehouse feature in your version, you must build a test logic on your own to compare the space above the last item on the last pallet in a rack cell to its maximum allowed height of this cell. I answered in a previous question all needed commands to get the reference to this product. Now you can get his topmost location value by evaluating the object method getLocation and project this 3D Vector into the model space. The z- component of this result vector is the height in a cell to ground level.

direct casting of a treenode to object:

.as(Object)

documented in:

https://docs.flexsim.com/en/19.1/Reference/CodingInFlexSim/FlexScriptAPIReference/Tree/treenode.html

method for a topmost vector in container space of the product

https://docs.flexsim.com/en/19.1/Reference/CodingInFlexSim/FlexScriptAPIReference/Tree/Object.html#Method-getLocation

project this vector from container space into model space.

https://docs.flexsim.com/en/19.1/Reference/CodingInFlexSim/FlexScriptAPIReference/Data/Vec3.html#Method-project

Maybe you have to cast container object into a treenode. The reference of model ismodel()

get z component

https://docs.flexsim.com/en/19.1/Reference/CodingInFlexSim/FlexScriptAPIReference/Data/Vec3.html#Property-z