I'm stuck on the lock in the room with the fireplace. I tried every combination of 4, 1, and 50, since those are the letters (representing Roman numerals) highlighted in red.
I am not sure if the code is randomized or not, but in case it isn’t, I am letting you know I managed to get past it solely by using the roman numerals found in the same room as the fireplace. Which means there is a combination that was missed after all. Also there was a number 9 in mine. IX = 9