Whether the 2 Eur tip is too little or too much is not the debate. It's whether the individual employee reasonably thought that the change was a tip and took it as that or stole it. Change left on top of a desk or bureau is legitimately thought of as a tip and it's entirely fair for the maid to have taken only 2 because she didn't do much of a clean up.

Forget it, move on and next time, don't leave cash where it's generally left when meant for others.