This should be fixable by making ProcessParameterPanel as Evaluatee and adding the concept of parent Evaluatee to GridField. With ProcessParameterPanel as parent/first Evaluatee and Environment context as secondary Evaluatee, we allow value from ProcessParameterPanel’s editor to take precedence over same name field in calling GridTab.
When launching process from line and process parmeter has default logic, it brings value from header instead of using from tab.