Capitano's sacrifice still doesn't make sense to me

Let me get this straight, Xbalanque established a deal with Ronova, one of the four shades, the "Ruler of Death", and the explicit words they say are:

Ronova: My domain is death, and its power comes at a great price... The question is, are you prepared to pay?

Xbalanque: I need that power. Only a hero can truely wield it, and heroes are not afraid of dying.

So just by reading this, you would assume that Xbalanque would pay the price, right? But in Mavuika's story quest we learn that he is a soul in the night kingdom just like any other, and even comes back to it after the quest, meaning that the deal didn't had any lasting effects on him.

Then what about the following/current pyro archons? Did any of them paid the price as they are aware of the deal (As seen by the whole scene of Mavuika walking on her...mind temple? Whatever it was but she saw the deal), and therefore is highly probably they knew about it and the possible consequences it would come with it? No, as since we know that Xbalanque went unharmed, it is safe to assume that all other pyro archon are just as safe, and if we talk about the current pyro archon...

So my question is, why a random outlander? Death is equal to all beings, sonner or later it comes, the pyro archons life is just as worth as that of any Natlanese, so in exchange for a power that comes with a "great price" Ronova just asks for...one life? Ronova would have been satisfied with Mavuika, but why? As a reader, it just doesn't make sense in any level.

And guys, I am not saying "Mavuika should have definetly died!", is just that the man who made the original deal is completely untouched by the consequences of the deal, the woman who used said power ended up untouched by the consequences of the deal, then what was even the point of making a deal instead of simply giving that power as a gift? If it were something like "The consequence is that everyone who owns the tittle of the pyro archon won't be permitted in Natlan leylines and Teyvat leylines after their death" it would have made a lot of sense, every pyro archon would be sacrificing themselves for their nation, even if they end up forgotten by time.

If I went a little into a rant, forgive me, but it has been weeks where I have tried to make sense of it in a narrative perspective, but I always conclude that this has to have been written by a toddler.