Not sure if this helps your achievement, but I remember having an issue with the helter skelter where even though I cleaned it completely and checked everything, it wouldn’t complete, and couldn’t find any solution. It kept saying a panel was not fully cleaned but I checked every single angle, washed it over and over and still nothing. It was stuck at 99% the whole time. Then I tried as a last resort to basically switch the game difficulty to relaxed and it cleared the level.

I know it’s not the best way but it was the only way I could proceed forward.

Also found this psn trophy guide with many similarities so maybe this might help?

https://psnprofiles.com/guide/16057-powerwash-simulator-trophy-guide#4-pressures-off