To effectively delete the effects of the reforms, one could eliminate all the build file references that say "and not marian_reforms" so that when they occur the velites/hastati/principes/triarii are still buildable. The units that say, "and marian_reforms" could be commented out of the build list so that they can never be built. That should force things to remain unchanged despite the reforms occurring. Haven't tested this though.

And the Praetorian Cohorts in the game have a stat error that allows them to be built early because they lack the Marian reform requirement. How do I know for sure it is unintentional? The Tech Tree foldout says "Praetorian Cohort (am)"--where "am" = after Marian refroms. This was impossible before the 1.2 patch, because building the palace triggered the reforms every time, but now it does not.