Some items/creatures show as translated and others not.
While playing with my old character, if I add a newly spawned item to my bag (that I didn't have already) and exit the game, the stored item gets translated when I log back to the game later.
So it would seem that perhaps the items suffered a change of structure/format at some point during development. And now two different formats for items are coexisting: the old one which doesn't get translated and the current one which does.
A fact that may contradict this supposition is that I have a buckler and a bardiche which are supposedly old (and thus should use the old format) and which get translated anyway.
Perhaps the format change actually happened before I acquired them and so they are already in the new format? I can't tell.