I think it would make most sense if we have the official translation updated as soon as possible, together with v20, so that other Polish users who have no idea about the site you mentioned could download it here, too. Would it be all right if one of the Polish translators sent me the lines by e-mail, so I could update the version? My e-mail is kulyok, at
yandex. ru. Because I don't feel very comfortable "stealing" it from the download you mentioned.
And when v20 is released, with all the bugfixes and updated translations, I would very much like if one of the guys from the site you mentioned could download it, check that it works in Polish, and take down the "unofficial" mirror, since it's really not our kind of thing.
(By the way, to anyone interested: if there's a German or a Japanese or any other unofficial translation of UB somewhere, please send it to me, and I'll happily upload it).