Engine doesn't need to be lowered. The solution is very simple and easy. Take your car to Toyota. Get the genuine seal and have it fixed there. Just make sure that they drain the CVT oil in most cleaner manner, in clean environment, in a clean pot and use a clean cloth strainer while putting the oil back. Then put the new gasket seal and the bolts shouldn't be tightened too hard. They should be tightened very normally.