A family of Microsoft word processing software products for creating web, email, and print documents.
AutoCorrect entries don't fire until you end the word by pressing a space or punctuation mark, which is why your shortcut doesn't work in the middle of a word. I think you're stuck with an ordinary keyboard shortcut in general, but if there are certain words containing the "ą" character that occur frequently, you could create an AutoCorrect entry for each one.