I’m using Max OS X El Capitan as a server OS, Win10 and Android as client OSs. Today I tried to install Karabiner and remap Ctrl to Cmd. That worked for the local Mac keyboard (USB), but didn’t work for either of the clients. When in a NoMachine session, I pressed Ctrl-Tab with no effect, whereas locally Ctrl-Tab switched windows. (I’m describing that verbously in order to convey a feeling of how I tested the behavior.)
DoubleCommand shows same pattern of behavior.