Edit- re read your post Rear adjustment;
Adjust the striker loop on the C pillar , it will pull the door in, if that is not enough adjustment, the rollers need to be adjusted in the mountings ( top bracket ) it may need to be moved out to allow the bottom to move in !
adjust in small increments. Close the door carefully after each adjustment
For font adjustments :
Look at the male part on the slider that lines up with the female part on the B pillar
The male part on the door can be moved to make the door pull in at the front.
Mark the original position vertical & horizontal before starting (use masking tape to the edge of the male part outermost )
Undo the top part (loosen 2 screws) move a small increment, tighten the two screws, close the door carefully
Repeat for lower part
Rinse repeat to top and bottom until desired effect is achieved.
You’ll find you’ve fixed the rattle in the slider at the same time !