A lot of users have trouble with adapting the language, as I had myself.
I run a wordpress site in German but the yak plugin kept showing up in English. I had a long way finding out that i have to rename the file "yak-de.mo" in the folder /lang to "yak-de_DE.mo".
The ending after yak- has to be EXACTLY the same like
You can find this line of code in the file "wp-config.php" around line #70 in the root folder of your wordpress site.
@YAK developers, please rename the language files or show this notice somewhere in your documentation.