In station room 4,when you remove a failsafe, you place if on the card instead of gaining it. Does this mean that it is not possible to complete a collect type diagram?
That's true for Room 2, not Room 4. And correct, for Room 2 you cannot gain points by collecting.
Room 4 has you completely all four sides of the diagram, you have to complete a collect diagram. Room 4 is completely passive in normal mode. No rule alterations or movements. (It does have some rules for Challenge mode, but those rules don't deal with failsafes.)