The objective is to be able to select between the free text searcher and a new Exact Text Searcher for Calculated Text Fields.
The latter makes the field compatible with the Statistics Gadget.
For example, if you want to create calculated fields containing the parent and child values of a cascading field, you can create two Calculated Text Fields with the following formulas (assuming customfield_11300 is the ID of the cascading select field):
Parent value from Cascading Select:
Child value from Cascading Select:
and select the "Exact Text Searcher (statistics-compatible)" searcher for each.