Cruiser ramming successes and their costs

Were there cases of cruisers causing major damage by ramming?

Yes, especially against submarines, but the danger of badly damaging the attacking ship made ramming an exceptional tactic.

Birmingham's destruction of U-15 demonstrates that a cruiser could sink a submarine by direct impact. Curacoa's loss after being struck by Queen Mary shows the catastrophic danger to a smaller vessel caught in a collision. Ramming could also damage the attacker badly enough to sink it. Dreadnought's submarine-ramming success supplies an exceptional battleship example. These risks made ramming an improvised expedient when an opportunity appeared.