Oh dear, I spent another 2 hours yesterday trying to get those two missing endings... and I couldn't manage it. I've had all four options too and yet they did not make a difference.
It's nice to know that there's an artbook with a guide but right now it would be really irresponsible for me to spend money since I got sent home to be in lockdown without my paycheck :(
To the devs: you just released this and I'm already yearning for another game from you ;D