From your description of your trigger - "a sealed box" - you may be correct - sounds very much like an aftermarket trigger unit with integral sear?? So far as the ones that I messed with, CG63 have a standard military Swede m96 trigger and sear. I can only assume that someone not really knowing what they were doing had replaced the trigger unit and did not finish the job. You are correct - usually there is a very tiny bevel needed on the leading edge of the cocking piece shoulder to allow that wing safety to engage. Then have a "check" sequence to ensure that the safety lifts the cocking piece off the trigger sear when engaged - so that the trigger can be pulled and released with the safety on, and that sear does so go back into place to accept the cocking piece when the safety is released - else the rifle will fire when safety released, because trigger sear was not in place.
Quite important on most any safety like Swede, mauser 98, P14, etc. that engaging the safety on the bolt shroud actually pulls the cocking piece slightly rearward - right off the trigger's sear - that way pulling and releasing the trigger re-sets it into correct position, so long as not being bound by poor inletting, crud, or whatever. Releasing the safety to "fire" should lower the cocking piece back down onto the trigger sear - if it is not there, the cocking piece just slams forward and fires the rifle. Can read an account of Jim Corbett taking a tiger that way with his Rigby mauser rifle - was very close - knew the safety made noise when released, so pulled the trigger, aimed, and fired the rifle by releasing the safety. He was around to write the story - the tiger was not, so it worked...