Another thing was the "Portal sides" property. Remember them? Well, now they work just as I wanted. You can shoot portals through them (just like "Grid" blocks), as soon as you're not pointing to their colliding faces. The images show better what I'm talking about:
Later today I'll try to fix (by myself) 2 other bugs: making coins output a signal when collected and making grids not allow light beams/lasers/gels to pass through them (actually, that's not a bug. I planned adding this, but now with "Entities sides" I can make them easier to specify what can or cannot pass through). That's it for today. Thanks for reading, and I see you in my next post!