I agree a second fine (or finer) grind through your smallest plate would probably reduce the chance of those 'fat pockets' & get a more uniform mix. For my recent 'franks' episode, my first grind was 4.5mm, then 2x with 3.0mm plate = a very smooth consistency with no detectable pockets.
The extended poaching time you gave the chubs (up to 165° versus pulling them at 152°) may have also contributed the fat rendering (hole-producing).
Good looking boloney, tho!
Those loafs would only last a few days in my house.