The verb "pić" means "to drink" (the amount is not important). The related
verb "wypić" has no English equivalent. Its meaning can be expressed by description (or context), not by any specific tense. It means "to drink it all",
"to drink to the last drop", "to empty the glass, the bottle", "to drink until nothing is left", "to finish or to complete... the drink".
Piłyśmy (już) sok - We have drunk the juice (already)
Wypiłyśmy (już) sok - We have drunk (all of) the juice (already)
(Wczoraj) Piłyśmy sok - We drank the juice (yesterday)
(Wczoraj) Wypiłyśmy sok - We drank (all of) the juice (yesterday)
I know! It's the same in Russian.
But it makes no difference as to "we drank" or "we've drunk" in English. I think the simpler translation for Polish past tense is English past tense, not present perfect which is more complicated for no reason. "We drank the orange juice," is much better than "we've drunk orange juice." Past tense to past tense.
I know that you know :) The point is that Present Perfect
is terribly misunderstood. The verb aspect in Polish is another story...
It is only logical to use Present Perfect whent time of the activity is not specified and refers to the presence, and Simple Past, when the precise time is given (or implied).
That's not true. Present perfect and past tense do not follow that hard rule. It's determined by context.
We've painted the house. We painted the house. Both mean the same thing without additional context. We've drunk the orange juice. We drank the orange juice. It means the same thing, so simple past is better because it's a one-to-one translation.
piłyśmy = we were drinking (as in, this is what we were doing); wypiłyśmy = we drank ( as in, we done drank, drank it all up, finished drinking the orange juice) ? Technically, I think the translation "we have drunk (the) orange juice" is (grammatically) correct, in this context. Except no one says that in real life.
I think we might say "we drank the orange juice" to indicate the perfective (that you finished drinking it) and rather "we drank orange juice" (without adding 'the') to indicate that that is an activity you were doing, without necessarily finishing it (niedokonany/ imperfective)