Chasing leaks in a pressure washer setup is just a fact of life. But Garden Hose leaks are common for a lot of people, even in a connection to a Kranzle. Usually people are able to get past the problem by tightening down the male threaded plug into the inlet of the pressure washer further than you think. What’s happening is there is a swiveling coupler that is loose until you install a hose or fitting. When installing the plug, you are actually creating a seal on the inside against a rubber washer. As the threads are tightened, the swiveling coupler is pulled away from the pressure washer and creates a tight seal as it gets tighter and tighter. This is the same idea for the female end of a garden hose as well.
It has less to do with the threads, and more to do with getting that coupler and plug as tight as possible to create a tight seal. Don't use ANY tape on the threads of a garden hose connection. These connections should be hand tightened, but some instances pliers do help. You want it snug and for the swivel to lock down and be tight. Tape or incorrect thread will inhibit this. Grab a pack of rubber garden hose washers from the hardware store. They may be better than was is included in your garden hose, QDs, Inlet, etc. They're usually a couple bucks for a bag of 10 or so.