Yeah, i am trying to level this second bed i got as it was not “perfect” either. By hand bending it i am pretty close, thinking i better leave it like this before it breaks or something! I have to put pretty much pressure to get some movement of the aluminium plate and i know there is a fine line here where it may bend to much. This bed was only warped in one direction, and fully flat in the other. But bending it back it showed a slight waviness of maybe 0.1-0.2mm i guess by eyesight.
On this bed i also shimed the plastic frame down so it is fully aligned with the metal plate.
I will need to find a magnetic bed, i have ordered one already.
and yes, i use a prusa satin sheet for my printer as the satin sheet is just the BEST ever print surface