I wonder

it's because there are three identities after hinata named their hero persona "chronoa", this chronoa is different from hinata and chloe, she's like a skill with a personality and will--a manas. now, when chloe disappeared to appear in a different timeline as the "chloe" who got transported with leon, the manas "chronoa" went unstable, and hinata couldnt handle it

so, when the body without chloe and hinata got sealed, the one inside is "chronoa"

So... How come chloe get transported again with other kids, when she already did with leon?

chloe said this in the recent chapter, either the timeline she's taken to is with leon, or with the kids

but from what i can see, it seems chloe's original timeline is when she was transported with leon to the cardinal world, but at the same time she disappears this time due to being "summoned" by the nobles of the west (remember the plot about how summoning is an open secret within the west council, it is also a thing in the east empire too), and due to this summoning, chloe meets the other kids in Engrassia, and is taken care of by the Free Guild led by Yuuki.

take note that being "transported" is different from being "summoned", here are a few examples:

transported characters: yuuki, hinata, chloe, leon, masayuki
summoned characters: shizue izawa, glenda, gale gibson, ryota sakaguchi, alice rondo, chloe aubert, etc.
reincarnated characters: maribel rozzo, rimuru, etc.

okay nvm here's a simple explanation:

chloe 1: transported to cardinal world with leon
chloe 2: summoned by a western kingdom
chloe 3: when hinata dies, she time travels 2000 years in the past with hinata's soul

she's in a time loop