Do you know for fact that floor tiles are suitable for a tack board? The cork floor tiles I have in my house are very hard, being impregnated with some sort of compound to make them wear-resistant. I doubt that push-pins would go in easily, or that the holes would self-seal.
Hi Peter: I don't know of anyone who impregnates cork floor tiles with anything. It is common practice to coat them with a urethane or similar coating for waterproofing, but it sounds like what you are describing are properties of the cork itself.
P.S. There are two type of cork floors. One is a tile of just cork, usually 3/4" thick. The other is a system of layers, usually of wood (called an engineered floor), with a thin layer of cork on top.