If you have an old trainer that is failing, the technical "fix" is to uninstall it, verify your game files via Steam (right-click > Properties > Installed Files > Verify integrity), and install from the Workshop instead.
: Delete your ArmaReforger cache folder in your local AppData. This forces the game to re-verify mod dependencies that might be blocking your trainer scripts. Arma Reforger Trainer Fix
uses the Enfusion engine, which obfuscates data like ammo counts (using XORing), you cannot manually fix a broken trainer script unless you are experienced with memory editors like Cheat Engine Version Mismatch If you have an old trainer that is