Any projectiles made by aliens should be able to press buttons and go through human portals.
Having any porjectile (both alien and human) pass through portals is definitely something planned . Currently the alien projectiles can activate any button that can be activated by damage, it is just that some buttons can only be activated by pushing (set by the mapper). I think the reason for that is in some maps buttons are meant to be activated only by a certain team.
Buttons : Human hand scanners so aliens cant open the door that is activated by the humans. The door would only open for aliens if they deal a certain amount of damage to open the door for like 10 - 20 seconds ( maybe longer ) .
Human gun projectiles ( That dont hit target straight away ) : Lucifer Cannon is one of those guns and if you quickly turn while charging the gun you can make the ball of energy ( that comes from luci ) bend around a corner or something