There isn't a single creature at its level that is stronger than an elite guard; even 7 unupgraded ones will be worse, but they definitely don't need to be fixed; the top unit should remain the top.
If you compare them to the existing ones, the current ones are not overpowered at all.
I don't know about the cavalry commander; I haven't downloaded it.
The duelist is weak against any upgraded horse; it has 7 speed (it can't catch up!) and nothing special; one magic fist won't even bring it up to the level of a standard paladin/champion, even on expert difficulty.
The templar is just a standard horse with 120 HP, bravery, and an aura of bravery; it's slightly stronger than a standard horse in terms of HP (+20), and that's it. It's far from reaching the level of a green champion.
And these are superior by an order of magnitude.