How to Update Seeded Comment with value from Custom Field

Summary:

We using a structured process using Gen3 OPA to achieve custom transaction approval. Rejection comments have to be mandatory and we have solutioned using custom comment field that is mandatory in case of rejection, Using Event at the Webform level.
The seeded comment functionality at task level does not have mandatory option, but we need to update the same using the custom comment field value.

The closest workaround could have been calling https://docs.oracle.com/en/cloud/paas/process-automation/rest-api-proca/op-tasks-id-comments-post.html but it requires current {taskid} which is not available for use as additional REST call within OPA.