QUARK BLOG THEME: Sidebar styling

I'm having issues modifying the sidebar contents in the Quark blog theme. I'm trying to get a second category to display it's associated tags in the sidebar. Also I don't understand how <h4>{{ 'SIDEBAR.POPULAR_TAGS.HEADLINE'|t }}</h4> becomes the sidebar title. If you change POPULAR_TAGS to anything else it won't display right.

Thanks in advance for any help!

I figured out that the /quark/languages.yaml was involved in my problem.
It's fixed now!