In this weeks Haftora - Melachim1 6:7 on the word Umakavos, Rashi translates as Dluta in Russian. To the best of my knowledge there are no other locations where Rashi translates into Russian. Why over here does Rashi translate into Russian rather than the standard French translation?
Asked and answered here.
it seems quite likely that this is a later interpolation; it doesn't appear in early prints of Rashi.
In several places, though, Rashi refers to לשון כנען, which was a popular term at the time for the Slavic languages (based on the equation of "Slav" with "slave" and the association of the latter with Canaan). These include Deut. 3:9 (שניר הוא שלג... ובלשון כנען), Shabbos 20b in Hagahos HaBach (פסולתא דזיפתא... עיטרן שקורין דוהינו בלשון כנען), Avodah Zarah 28b (חיפושתא... ובלשון כנען קרוקי"ם) and 51b (דסחיפא לה משכילתא ארישיה... כלי ארוך ובלשון כנען אקדון). Some of these might indeed be Polish, although I don't know.
Rav Eliyahu Essas, one of the most respected Russian rabbanim, answers this question on the verse Melachim I 6:7 here (in Russian though). The basic sense is that it is a typo.
If one replaces the samech in rusi with mem, and they are very similar in print, one gets rumi or romi - translation to Latin, and indeed the word dolatum means to shape stones and in some variants of Latin, the word is dolita, almost identical to the one cited by Rashi.