So you rescued three worn out high production hens, that would have otherwise been butchered?
You have done a very good job caring for them, as can be seen comparing their condition of then and now.
The problem with these hens often is, that they are prone to reproductive disorders (internal laying, peritonitis, ovarian cancer, water belly etc.) that often entail crop issues as well.
Regarding their diet I would recommend to stop the corn and all other treats and just feed layer pellets plus additional eggshells. Oyster shells and grit should always be availabe.
Hopefully your Paulo will recover with the right treatment for her crop issue.