IMO the rear loop length looks fine. It's not the length per se, it's how it aligns entering the RD fitting, and it looks straight on, which is correct. Howeer, I see you have interanl routing, and these can be (don't have to be) prone to friction at places like the bend in the BB. If there's any place you can access bare wire pull it away from the frame like a bow string and observe if the RD move smoothly or in small jerks. Also shift to any gear, then use the lever to shift half way to the next (not enough to latch the click) and let go and see if the RD crisply returns to correct trim. If so, it's fine, if not, you have friction someplace along the line.