Translation

Hi,
with which plugin you’re trying to translate them?
As per theme reviewers rules themes hosted in wp.org (as well as plugins) are translated on https://translate.wordpress.org/projects/wp-themes/hueman
Additional languages files, for not fully translated locales, can be found in hueman/languages

Though it doesn’t seem you want to translate those strings, rather you want to change them, right?
Those strings are in hueman/parts/post-nav.php which you can override in your child-theme, if you want.
https://codex.wordpress.org/Child_Themes

Hope this helps.