In my experience what happens in actual play is a ruling that ignores all the nuances.

The stealth, vision, and other bits are spread over 3 to 5 places in the books. The DM hasn't exhaustively read or memorized them and doesn't haunt forums where they're discussed. There aren't examples or specific advice in the rule books.

Therefore the DM rules that A is hidden, or calls for opposed stealth & exception checks, or if B is a PC and doesn't specifically say they're looking for invisible/hidden people then A is hidden.

Light, dark, invisible, etc., just never seems to matter.