How can I enable spell check in Plasma settings? It seems I can’t add any other language than is already there?
And also a question about Plasma Translations (Regional Settings → Language). How and where can I configure what is getting translated? I added some languages to the list and now terminal output and some apps UIs are seemingly randomly translated, it doesn’t look consistent.
Install aspell then it all works, solved it for me
Thanks, I just did. Still can’t choose a different language in Plasma settings… Is it supposed to be like that?
Where is the spell check used anyway?
I’d probably be able to tell if at least the Help button was working there 
I am new to Plasma, just exploring the settings and trying to configure it to my liking…
I was able to add another lauguage and log out and back in. But i don’t know how it works.
Okay… i went in the terminal and it’s French!
Really? How did you manage?
I don’t know, try to type some nonsense in some app 
You added it to the Language list? That’s what I was talking about too, half of the terminal output now will be translated…
It’s all in french as i added french? The save window was also in french?
I see the Konsole’s UI is still in English. It’s messed up. If you add more languages you will start getting things like that
Given that the default language is still english.
It’s strange…
Yes… i’m not sure how it’s supposed to work. Not sure i would use it? I can see if you want to change language on the fly maybe?
It’s not working on the fly. We have to log out and back in.
I know i’m just saying it would be handy if you could change it on the fly for a purpose and then back again. Like for a screenshot or something?
I agree, it was very convenient.
Was it working for you out of the box or did you do/install something extra?
I probably should have mentioned this from the beginning, but I don’t have the full Plasma install. It is a minimal installation, according to @dalto’s recommendation, which normally works very well, but some missing functionality can be expected. I am still only discovering what I’ll eventually need, so I may need to install some package(s) to get it working.
I don’t remember anymore, but I probably did a full Plasma installation. And I additionally installed aspell-ru to check the russian spelling.
Thank you! That did it. I initially just installed aspell package, but didn’t install any dictionaries 
After installing them I can choose the spell checker in the menu. No additional package from the Plasma group was needed.