The safest workaround in this case is the following:
Add all your language columns without assigning languages and
leave kvoctrain
. Then load the
vocabulary file in your favourite text editor and enter the language codes
manually. The first line with vocabularies contains the language codes
in the "l" tags:
<e><o width="105" l="en">gänzlich</o><<t width="140" l="de">utterly</t></e>