The AI does change is some ways. The fact is well known that the AI in early Eras goes for Rogues first. In later Eras the AI does not Go for Rogues first.
I’ve never heard nor seen the AI do that based on age.
What I have seen is the AI in the Continent Map and PvP Arena ignores rogues, while other areas go for rogues first.
What you may also have encountered is
the battlefield scaling mechanic that kicks in at Progressive Era and above
What this translates into is two things.
1) Instead of your Rogues always being in firing range before they can move, they're potentially out of range on that first round
2) Your Rogues gradually shift from having more movement than your regular units, to now having less movement.
Remember how Fast Units in the earlier ages were a bad idea purely because they had so much movement points that they were guaranteed to always rush ahead of Rogues (coupled with their behaviour mechanics)? Well now that starts to apply to most of the popular units of each age as you go higher up. It's not the AI for targeting that changed, it actually remained the same, it's the increased movement values on each unit leaving the Rogues far behind on the map along with a increased movement cost required. By the time the Rogues get into range to be attacked the regular units are more likely to already be dead in certain ages purely due to range of movement
That seemed true till Venus, in Venus it seems to go after rogues again
Looking up popular units for Venus the go-to combo seems to be Power Dragon + Rogues
Rogues Movement: 14
Power Dragon Movement: 12
Again, unless you're using other units in Venus then that's a movement range issue not a targeting issue. You need the Rogues to go ahead of your other units if you want to improve their chances of transforming