I know it's not the same as having Paradox expand the religion system, but my mod does a lot of what is being asked for here: Sikhs exist, there's a Reformation-like event chain for them, and since religious minorities exist, religions like the Jews and Jains are in it as well.
EDIT: Whoops, it seems I've already posted the same thing in this thread. Sorry about that.
EDIT: Whoops, it seems I've already posted the same thing in this thread. Sorry about that.