In short, my KDE desktop is English, and all KDE control center settings are set to English (switching them back and forth does not help), but in the command line LANGUAGE=jp and LANG=jp_JP, correspondingly some programs I run from KDE desktop display their GUI in Japanese. What is the primary place to fix these LANGUAGE and LANG (and other environment variables I may miss)?

In not-so-short I downloaded Knoppix image from Japanese site, booted it with lang=en (it was all English when working from CD), ran knx2hd and got what is descrived above on HDD. Not that I completely could not read Japanese, but still English would be better for me :)