HI Marcin,
This can be achieved easily, some things to keep in mind.
1) Each file type will be a separate file format entity in Delphix, they can reside in same ruleset though.
2) Masking a same file ( file format) with 2 different algorithms will require 2 rule-sets.
3) Wildcard Regex Expression can be used to indicate file name/type in ruleset.
4) Source/Target can be changed at run time using "Multi-Tenant" functionality.
An API to do create ruleset/ other features dynamically is under development and will start shipping year end.
--Hims