If you have a scratch you think you need to wetsand first, you're miles away from any help an SMR can give you. I hope you dn't have to go that far - but as suggested start lighter. I've had reasonable success spot treating scratches with Meuiars' Scratch-X. It leaves a pretty darn good finish. If you have haze left from any step, you need a lightger compund to get rid of it - but PROPERLY APPLIED even 3M FI-II can leave a really good finish. IMPROPERLY APPLIED, less aggressive 3M SMR can leave a haze behind. Proper application means working the living @#$% out of the compound so that the abrasives break down all the way into polish. By hand this is possibly impossible, with an orbital it take more time and pressure than you might think.
Meguiar's Swirl Remover 2.0 isn't very abrasive but has outstanding filling capabilities, and is safe to use by hand.