So the throne room codes can be combined to solve the sewer's QR puzzle without a QR reader, but it's really convoluted:
Stack the 16-cube door temple's code ("newer throne") above the temple warp zone's code ("dilapidated throne"). Then read the coderead the code vertically from left to right: RRLRRRLLRLLLRLRL.
If you solve the QR puzzles normally, the throne rooms will turn gold ("completed") on their own.