How Can I populate HR case description in HR Task

I am having issue populating the description from HR Case to HR Task, I have a rich_description field on both HR case and HR Task and I am setting up some fields on HR Task via HR Template  but it's not able to set the description from HR case in HR Task. Since rich_description field created on case level so {$parent.rich_description} not working as parent will be task table.
I have also tried in workflow script but that is also not working. Can someone help me who came across such issue?

Thanks,
Anmol