Don’t think so! AFAIK the Librem 15 v4 supports HDMI 1.4 at most, so it should do 4k @ 30Hz—what the Librem site mentions—which is fine, I didn’t buy this laptop for gaming 
It’s just, right now, moving any window to the other screen results in ludicrously large fonts because of the resolution difference.
I just checked and I get the same EDID blob (in /sys) when it is plugged into the Librem laptop. So that part gets read alright… I don’t know what this cable is but it works to get 4k resolution (also at 30Hz) when connected to another computer.