Hello,

This the filtering is on the choice table. maybe you can create a lookup select field on sys_choice table and filter with the table - change_request and element - subcategory and dependent_value - Business Systems options

ex - 

javascript: 'name=change_request^element=subcategory^dependent_value=business_systems';

I have created a test one with following details

table - change_request

field - category

language - es