Is my microwave damaged if I can smell the food inside it?
Microwave doors don't have an airtight seal; the window between the electronics and the cooking compartment is also not airtight, and the electronics are cooled by a fan. It would be surprising if some cooking smells didn't escape. In practice, every microwave I've ever had allows me to smell the cooking, from the very cheapest to some rather fancy ones with grill and convection. 

This means that being able to smell the food cooking says nothing about the safety of the microwave, and you have no need to worry (unless there are other indications such as damage)