Sorry for not being completely clear.
Yes, the route need to exist for the return traffic.
But the main issue here is not correctly understanding how route policies work. There is an import policy created for the the workstation route. But it is important to note that policy does NOT create routes it can only act on routes that are active in the routing table for import or export actions.
In this example the workstation route does not exist in the inet.0 routing table so it cannot be imported to test.inet.0