You can turn the options for cheats off right after you convert the world and still earn achievements, as long as you don't go into the world and save it with the cheats enabled it won't mess it up, although they need to fix it so the default after conversion is not to have cheats enabled.
Sorry, it was for version 1.12 beta so I assumed that was under unreleased version as I didn't see an option for the 1.12, thank you for letting me know!