How to changing language?

Add-ons
#1

Hello,

I have trouble changing the language for my add-on GroupSpeedDial 2.
I’ve changed general.useragent.locale value in about:config page to “sk” (for Slovak) but after restarting Firefox only addon short description in about:addons page is in Slovak, all other labels are still English.

#2

See https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Internationalization#Testing_out_your_extension