The MiSTer project isn't as simple as setting up a pi, however it's far better in terms of Lag, how it handles monitors, and in some cores cases accuracy for sure. It's a tradeoff. I'd suggest if you have trouble or errors and such, the best thing to do with projects like this is start from the top.
1. Reflash your MicroSD card, but this time with the suggested method with Mr. Fusion. (
https://github.com/MiSTer-devel/Main_Mi ... etup-Guide) . if you are using a windows pc, prior to running the mr. fusion application, i suggest starting command prompt as administrator, typing "diskpart" and enter, "list disk" and enter, "select disk #" (replace # with your disk) and enter, then "clean" and enter, and then "create partition primary" and enter, then "exit" and enter. That should clean up the MicroSD to brand new, this helps when reflashing MicroSD's that have multiple partitions.
2. then boot the new MicroSD and let Mr. Fusion do it's thing. After that's done, and if you have an ethernet connection to the MiSTer (personally as wifi can be low performance), then run this -->
https://github.com/theypsilon/Update_All_MiSTer (or alternatively if you don't want to run it on the MiSTer, use his Updater-PC option and follow instructions accordingly after plugging the MicroSD into your computer. On fresh setups I prefer to do this method).
3. then load your games, load the core, and try it out.
If all this doesn't work for you, then it's likely there is a hardware problem somewhere as a result of improper setup or something else.
I also do get the urge to get something that "just works", which personally the Pi isn't that simple either in my opinion and has so many drawbacks that it aggravates me more than the MiSTer project now lol. Pi4 screen tearing on HDMI is maddening and very hard to fix, and depending upon emulation distro it can't yet since pi4 gpu drivers aren't fully understood even still.