Thank you very very much! :)
I believe you have the correct ruleset, you just need to "loosen" it up a bit, or redefine it a bit.
Vs lbh ybbx ng gur 3eq naq 4gu chmmyr, lbh'q abgvpr gung gur ehyrfrg vfa'g fgevpgyl nobhg gur gvyrf orvat pbzcyrgryl yrsg-nyvtarq jura fgrccvat ba yrsg sbbg naq ivpr irefn - ohg nobhg jung vf gur "zbfg" yrsg (be evtug). Gur 5gu chmmyr whfg gnxrf guvf gb gur rkgerzr.
If you'd like to discuss it more or for me to explain something in more detail, let me know!