Easy way to remember:
The focal length is printed on the LENS, not the BODY. It is a property of the GLASS.
A 17mm lens is always a 17mm lens no matter what you mount it on, J1, m4/3, APS-C, FF, or MF.
A crop BODY is what the BODY does to the image.
When you mount a 17mm lens on a Crop Body, it is the Body that does the 'crop' or the 'focal length multiplication' or whatever you want to call it. 17mm times the 'crop factor' of 1.6x = 27.2mm, means that the image produced is the same as if you put a 27mm lens on a FF body.