I was watching the video in this game and there was something that didn't quite sit well with me. The Carrion Lancer makes the charge but because the carrion is only one tray, he's able to decide whether that's a front charge or flank charge. I'm pretty sure they're right per the rules, I guess I would just like to see an exception made if it was a single tray like that.

Yeah, single trays that hit on an enemy's corner can decide which way that they want to go.

It's also possible to do it with wider formations but it's less likely as you need to hit at the right angle. I'm guessing that being able to choose which side of a defending unit you want to be on is going to be one of the strengths of the Leonx Riders' 1x3 formation.

As long as the front edge of the Carrion Lancer is what hit the Rune Golem, they were attempting that right. If the corner of the Carrion Lancer hit the front edge of the Rune Golem, the only option is how he ended up.