Finally! Someone addressing this problem! Chrome is no less important or significant than Mukuro, even when he is finally released from Vendice prison. She just, what, few months met Mukuro and she already grasped how to make illusions? And later, hold her own in the TYL!future?

And well... my personal opinion, Chrome is the full time Mist guardian, while Mukuro's part time. He's too busy scheming after all and he's mentioned that he didn't want to be associated with any famiglia. If anything, it's Chrome who's the official Mist guardian.

So you can see me cheering Tsuna on for straighten things up by force, if necessary. Go Boss!