There are various databases where people discuss such things and as many such databases are just made from submissions in a forum or scraping from some other database then not all will be tested and confirmed as working.
Usual things to check though/what you will be asked in such a thread.
Do you have the right region? Not so much a thing on the 3ds for cheats as things are usually fairly smart on this front but I note it anyway.
Do you have the right version of the game? Game updates are a thing for the 3ds and they could easily change memory locations compared to older/newer versions.
Are the cheats the right version for your cheat device/custom firmware/emulator? Less of a thing in this than some older systems but I note it anyway.
Do cheats work in any other games? It it is some form of user error or you have failed to set things up then no point chasing down individual game issues if it is system wide.
If you are reasonably sure the above things are correct and have cheats working in another game then next step for most is only putting individual cheats on at a time to see which one causes the crash.
is there a compatability spreadsheet out there that says whether cheats work or not?
