I was going to leave a bit of it to creative license, (Mainly having the Toa masks appear under the Powerless/Noble Kanohi after they change, with the old ones popping off. Specifically for Hura. And yes, Vhis technically has a Volitak shaped Huna. I just felt it'd be cumbersome on the cs.) So a subconscious Suva switch could be the cause. Or we could say it was the Great Spirit and leave it at that. Or their latent Toa energy reacts with their id so they match what they think a Toa is, including their Kanohi suiting them and this vision. And in a world of Protodermis, who's to say that something can't happen just because it didn't yet? Like, the Toa Mata had the chance to become Kaita and earn Golden Masks, despite the Toa Metru not being aware of these possibilities. I mean, there's a sentient mountain and a being constructed solely of (Energized?) Liquid Protodermis.