>>powiem tak - any + singular countable noun = uwazane za niepoprawne (chocby nie wiem, co >>mialoby to any znaczy - czy jakikolwiek, czy jakis, czy jeszcze cos innego); a + singular countable >>noun = jak najbardziej poprawne
Yes generally but not necessarily. If “ANY” is stressed, it can be used with singular countable nouns under certain conditions and it is by no means unacceptable even “by the book”.
“Is there ANY train to Cracow tonight ?” (‘any’ is assertive here with the meaning “ it doesn’t matter which “) I guess this is exactly what the asker had in mind.
“ANY train at all would be better than none” ( ANY is intensified by the postmodifier ‘at all” ,which makes it even more assertive )
And there’s also another exception when the NP is postmodified restrictively:
“Get me ANY train YOU GOT there”