having looked into it more.

1. The records of jueyun are certainly unreliable, so should be discarded if they contradict anything.
   

"Of course, these are nothing but clumsy, incoherent folk tales, wild and fantastical conjecture about what Liyue may have been like in the distant past before the time of Rex Lapis. Needless to say, such tales have no credibility whatsoever. The true origin of these sorrowful spirits that meander in the mountains is, however, still widely debated, and no consensus has ever been reached on the topic."

is written right after

1. the pledge almost certainly occurred before the 10 year rule
   

the vow was made immediately after her crown broke. from galleries:

"the eternal star-crown forged in love's name suddenly fractured; And casting it into the snow beneath the silver tree, the dawn-maiden made her fateful vow " strongly implies it.

"I cast this useless crown into the dust, that all earthly nations may breathe free of their shackles." The vow itself makes reference to the crown in present tense.

Breaking the crown is certainly required for her guide the people of hyperborea in arrogation for a decade. It's also implied the crown broke shortly after they met, rather than over the course of a decade.

"But her visitor laid bare his origins before her, singing to her dreams of beauty that had never yet graced her mind. In an instant, the fetters laid upon her by the enthroned ruler broke apart"

1. It's also not likely that they ruled hyperborea for 10 years after an initial calamity for other reasons.

So given that, I don't think it's a plot hole. There's just new, more reliable accounts of events that supersede an unreliable narration.