It's been a while since I've played Magic Sword. Was there a timer or graphic on screen that indicated the timer you are looking for? One of the things that made the timer easy to find in Castlevania was that the time values in RAM changed at the exact same time as the numbers on screen, so all I really had to do was have the play screen and the RAM viewer on screen and then just sort of focus on all of it rather than the details and it was easy to see what on screen was synced with the values in RAM. That was really handy when testing a bunch of the other values in RAM because once I started to run out of time in-game I could just throw some random numbers in and have all the time I needed.
It's not a visible timer. The player just suddenly loses health at periodic intervals. It's a bit of a sneaky thing, as its infrequent enough players may not notice apart from taking actual hits. But if you stand there for a couple minutes at the start and shoot whatever comes at you, you'll notice the health bar occasionally dropping on its own.
Then the process would be like:
1.) Start a new Relative/Comparative search.
2.) Wait a couple frames.
3.) Search for a smaller value.
4.) Repeat until only a few possible values remain.
5.) If no results found for a smaller value, try the whole process over looking for a higher value.