You cannot invoke a validate rule from a data transform
Rules of three types can reference validate rules:
Flow action rules, to validate user input
Activities, with the Obj-Validate method
Correspondence rules, to validate user responses to prompts
To execute a validate rule during initial entry of a work item, create a validate rule named onAdd with a work type as the key part. The standard activity Work-.Add causes a validation rule with that name to execute.
You can also create a validate rule called Validate that will run when a work item is updated.