Hello,
Your request seems to be a great fit for Mendix OQL (View Entities - Replace)
There's the REPLACE function that may be the perfect fit for this task.
Try using view entities and see if the following query is what you need
SELECT
REPLACE(T/TechnicalName, 'PROC_STEP_', '') AS UserFriendlyName,
COUNT(T/ID) AS TotalTasks
FROM
YourModule.Task T
GROUP BY
UserFriendlyName
Hope this helps!