Please use this plugin https://wordpress.org/plugins/loco-translate/
After installation go to WordPress Admin -> Loco Translate -> Manage Translations.
Click on your language, I believe it’s sv_SE.po, you will be redirect to it’s translation page.
Click on sync button, you will see that missing strings are updated.
Then Click on save and it will generate the updated sv_SE.po and sv_SE.mo files.
Use the “Filter Translations” search input, to search for the string that you want to translate.
Do your translations.
Remember to click save button after each translation!
Hope this helps!