Alright then. GreatWyrmGold, the world's greatest not-a-kid detective between the ages of 14 and 27 in the western half of my county, is on the case! Besides, I like having an excuse to get back into this game with its delightful sense of humor.
Test #1: Go straight from the introduction to the bedroom to get the gun, then pose with the gun in the bathroom, then...shoot the key down or something?
Result: Same crash.
Test #2: Reload save, grab the candle, pose with the gun, burn the string.
Result: "The air around this candle is hot, and according to physics, hot air rises..." No key, but I did see Jam consider the potential arson her plan could cause, which is nice. Especially since I've seen ending 16.
Test #3: Save, then try the gun just in case getting it to work makes them all work.
Result: It did! Cool.
Test #4: Save, reload other save to get meterstick.
Result: Didn't even have to re-pose before it worked. Weird, but probably useful. And definitely convenient.