The actual policy rate will, therefore, differ from the theoretical neutral rate if the underlying parameters – actual growth and inflation – are away from their respective potential or target rates.
One of the workhorses of international macroeconomic theory, the Mundell-Fleming model, dealt with precisely this issue some 40 years ago. And you are familiar with the result that, as long as you operate a flexible exchange rate, monetary policy becomes the more effective the higher the degree of capital mobility is.