It seems the most reliable way to get the right-click to work with two fingers only is explained here and is the one referring to editing synaptics.conf. synclient doesn't seem to work. Having said that…seems like a had a note to do this:

synclient RightButtonAreaLeft=1180

synclient RightButtonAreaTop=1180

update: did this, then edited /usr/share/X11/xorg.conf.d/40-libinput.conf 

    Section "InputClass"                                                            

        Identifier "libinput touchpad catchall"                                 

        MatchIsTouchpad "on"                                                    

        MatchDevicePath "/dev/input/event*"                                     

        Option "Tapping" "False"                                                

        Option "AccelProfile" "adaptive"                                        

        Option "AccelSpeed" "0.3"                                               

        Option "ClickMethod" "clickfinger"                                      

        Driver "libinput"                                                       

    EndSection