Hi, the last override package on this side:
getk2.org/documentation/tutorials/item/77-k2-template-override-package-comparison
is for K2 2.5.1.

Can this be used for K2 2.5.7 too or will there be a new override package?

If you're looking for override packages, they're all posted in this Override comparison article . It looks like future ones will be posted here. (v.2.6.1 is the latest as of this post.)