I'd be very interested in how to alter Legends' AIs. Truth be told, I only noticed Lancelot's behavior while testing a small graphics mod. It really bothered me that Alfred and Beowulf aren't available in regular skirmish. So I replaced Vlad's interface, fx, binks, text and castle files with Beowulf's. Their army comps are roughly comparable, since staples like Saxons and dragons are there. The big difference being the siege units and vampiric creepers. Under usual circumstances, I wouldn't have noticed the macemen, but I ended up paying more attention to the AI during a test match. For the most part, I wanted to make sure Vlad's AI can function with Beowulf's castle. This was when I noticed the macemen but dismissed them as event units. But then they kept showing up during further testing, including matches against Lancelot. This was when I decided to do the initial 1v1 test against Lancelot.
Honestly, I also find this pretty amazing, since this means there's an AI that uses macemen in the game.