I'm afraid I don't get the point.
Do you mean that typing "aaa" (3 times a) in the Replace column, and then the whole alphabet in the With column, you get all the alphabet just typing "aaa" on TextEdit, but not on Nisus Pro?
If this is what you mean, then I succeeded on TextEdit (and Mail.app) but NOT on Nisus Pro (nor on Pages). Yet, Nisus Pro has a system of it own. In NWP open Preferences > Quick Fix, select Fix typos, and add your options. Alternatively, you may use New Glossary instead of Fix typos.
This might solve your point --provided I really understood it. Otherwise, please excuse me.