What is the "Universal Post Function"?
The “Universal Post Function” provides three different actions to execute after an issue is transitioned: Jira REST API calls, variable definitions, and logging to the app log. Additionally, you can access and use the post function event payload as variables in your universal post functions.
Atlassian is currently not offering the possibility to call other post functions within post functions, see https://ecosystem.atlassian.net/browse/FRGE-1230. Please feel free to vote and/or comment the linked issue in order to help us being able to provide this functionality also for the Cloud version of Workflow Enhancer for Jira.