language support in 12.04

[Thomas Blasejewicz]

Good evening
The trouble maker speaks up again.

I am trying to use (X)Ubuntu on three different "experimental machines".
Two running 12.04.
On those two, I wanted to see how this "language support" thing worked
AND install English as the interface language in one, which is currently
using Japanese.
On both of these machines (one at home, the other in my office) I get
the same kind of error:

Could somebody please explain what this means and what I am supposed to
do about it?
Is this "Language support" thing not supposed to work all by itself?

Thank you.