First of: I had my KDE in german, but I changed it to en_US (already some time ago).

When I use in Akregator the internal Browser to comment on a blog post (in english), there is a problem with the spell check:
Except german any word is underlined,
when I right click on a word there is no suggestion,
when I choose "Check Spelling" then it says everything is OK (even though words are underlined),
however when there is a wrong spelled word the dialog pops-up (with en_US as dict selected) and I can correct it, after that all underlines are gone...
However if I type further words they are underlined again (correct or not correct).

In system settings preferred language and dictionary is en-US.
I didn't noticed any problems in other apps.
Already deleted the akregator config files -> no change.

So it seems, there are somehow traces from the former locale. How do I get rid of these?