I have used those Paterson plastic reels many times and once you master loading, the film stays nicely in the grooves but it is a bitch to get in the grooves. I suggest you practice loading with the ruined negatives in the light first and then in the dark. It looks as if the film is not flat and crinkled on the roll. Can't tell you what caused the splotches but might have something to do with the film not loaded properly so no real agitation. Try test loading and I also always used the twirling on Yankee tanks but did the upside-down agitation with Paterson.
Please re-read the thread and look at the photos, especially the last one. The film is
too wide. It's been measured with dial calipers. B&H has been notified, it's a QC issue. Rerapan is cutting 120 down to 127...poorly.
The mottling is called reticulation, and I'm told it's caused by humidity and heat. This may have been caused in the bag while I struggled to get the too-wide film in the reel, or possibly before it was ever sent to me.
The film is special order. It took 3 weeks to arrive. I put it directly in the refrigerator, exposed it a week later, and developed a week after that. So, it was either in the bag or before I got it. Either way, it's still too wide.