It's for a version that is obsolete, as it will be replaced by 2.0 soon.
There is no localization framework in place yet, so simply translating all the strings in code means the entire thing changes language for everyone with no way to switch during runtime, so I'd have to distribute separate packages for all languages then, which is impractical. There are also no plans to introduce localization, so your efforts are wasted on this either way.
It looks like you downloaded the repo and then submitted the containing folder, which is not how PRs are done.
Translated in to Russian (no core)