Add transition rules(postfunctions, validator, conditions) created by forge app to workflow via REST API calls from Forge APP

Forge
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1

Hi, I am trying to fetch the workflow rules and add new postfunction, validator to an existing workflow transition via the Forge App. Here is the API link
https://developer.atlassian.com/cloud/jira/platform/rest/v3/api-group-workflow-transition-rules/#api-group-workflow-transition-rules

Anyone successfully able to add rules to workflows using these APIs. I am getting following error with the GET API:
errorMessages: [
** “We couldn’t retrieve information about your workflow. Try again later and contact Jira Support if the problem persists.”**
** ],**
** errors: {}**
}
How can I get the id of a rule from the workflow design screen?

Thanks