I'm not sure how I'd display a number tile without a parallel event, and since there are 46 tiles for blank spaces that means 46 parallel events. Also, the switches A1-A9 for example, require a constantly running "check" right? If it was a one-time event, then if the player makes a mistake they couldn't change their answer. That's why the switches turn off and on, to change the display, and you can change the tile variable. It also just works fine for me and shouldn't be broken. Same with Jimmy's Adventure IV. If you push the barrel into the right spot, you then press Z again and it should disappear and make a confirmation sound effect. The barrels going into the right spots then unlock bridges which require switches to be on. Again it worked a million times for me when I made the game and to this day. If it doesn't work then uh, sorry lol. I appreciate you trying them though, glad you had fun with the sudoku puzzle at least. I'll use an updated version of RPGMaker if you can send me a download link (I've been looking for RPGMaker XP forever and can't find links and don't trust piratebay downloads). I can't pay for it and even if I could I don't want to use Steam or whatever. I hate Steam.
Viewing post in Arnold and Gretchen jam comments
No, they don't need a constantly running check. Think about it. The only time you should check for when you get all the numbers is the precise moment you enter a number, not a parallel event, it's extremely wasteful. And changing the display of the numbers only needs variables, not switches, it's hard to explain, but the events can change pages without needing a separate parallel event. You already have a variable, that's all you need.
Come to think about it... Wait for a bit. I'll make a prototype with my own version of a code puzzle and show you how it can be done better, without it turning into spagetti and relying on so many parallel events, and I'll send you a link so you can look. That is if I'm right... If I'm wrong I'll eat my words lol.
Anyway, here's my own version of a code breaking puzzle using event numbers...
https://barako-the-pirate.itch.io/code-breaker
As you can see, you don't need parallel events for this particular thing you wanna do. Everything is done through a common event and the boxes in which you input numbers in. Far, far less for you to maintain and create.
Hopefully it's useful to you. If not, it's certainly useful for me! Your game gave me great ideas for number inputting puzzles in my own games!