I played the campaign about 6 months before Reforged, then after release. There are some levels that are strangely easier/ai less aggressive. Dont recall specific mission, however there are number of people also claiming something is changed with ai in reforged grievance list.
I can try to find example within a week or 2 if no one else knows.
The grievance people had was that the Reign of Chaos campaigns used Frozen Throne upkeep (40v50 for low, 90v100 for max) and the attack type system (in RoC, piercing replaced magic type attacks). Though people complained about this, in many ways using the Frozen throne data actually made RoC missions harder, since RoC old data allowed mass towers to wipe out heavy unit waves that should never have died so easily. So, for example, in the final mission for orc RoC, infernal waves and fel orc attacks are now a serious issue, since massing towers cannot just obliterate them as it was in the past.