Hi @Anonymous,
If you are using Windows 10, would you please take a check for which language is set as the default under Settings->Time&Language->Region & Language?
You may change the Windows language preference to English, that would have the PowerApps studio App language switch to English as well.
Click the English language, then click Set as Default.
Do this would change Windows Display language in English.
It would need some time for PowerApps studio (UWP version) to switch the language.
You should be able to use Swedish keyboard after you switch to English language.

Currently there is no changing language option available within PowerApps studio (which I think @AndyPennell should mean this), if you would like it to be added in the future PowerApps studio version, then please submit as an idea.
Regards,
Michael