You have added extra search criteria to the search screen for a task and can view that criteria from the Identity Manager UI. However, the new search criteria fields are not exposed through TEWS. For example, when added to the search screen for a View User task, the new fields do not appear in the generated WSDL or in SOAP UI for the Subject of a View User Search. Why can't you see these new search criteria when accessing the task TEWS?
The WSDL for the Subject section of a task is auto-generated and includes various possible types for the object of a task. It can't be changed during generation of the WSDL. The subject could be user, a role, a task, etc. depending on the task that is being executed, and usually this section is filled in based on a preceding search query that retrieves the object and sets it as a subject for the task to work on, via the task's search filter object. It is typically taken care of internally if and when needed. For example, in a View User task you do not need to use the Subject in SOAP UI, but should use the Filter section. Other search criteria, such as any new fields added to the search screen in the IM UI, can be added to the Filter section as needed.