Changing language for dates used by a plugin

Hello. I am making a website that is in swedish, and I am implementing the events calendar plugin. I have gone through all of the css, java, and php for the plugin and wordpress itself and changed all the instances of Sunday (for instance, I did it with all the day/month names) to S?ndag (swedish), but the events calendar is still showing the date in english. Where is this plugin calling the date class from, and how can i fix this? I am proficient in css, php, and java, so I can fix it myself, but I don’t know where to change the names. I was hoping to not have to go through the entire plugin line by line and find this out manually. Any help you can offer would be greatly appreciated!

-Mark