In Charts 8 (Windows) I gave it the following flightplan:
KSLC/16R CGULL1 TWF DCT PDT CHINS5 KSEA/16R
My runway is also clearly set to 16R under “Runway” in the Origin area of Flights.
However, the charts clearly show me taking off from 16L. CGULL1 supports both 16L and R.