Well in my experience coolant smell in the cabin means a leaky heater core or connection to it. The added factor of liquid only when the car is tilted tells me it is pooling somewhere and can then leak out when the car tips a bit. If it is leaking you should see a drop in coolant level over time. Although, it doesn’t take much to create a smell, therefore it may take a while to show a drop in the water level in the radiator. I would climb under the driver’s side of the dash and find where the two coolant hoses connect to the heater core and check for any signs of leakage.

Good luck!!