Cracks in wire sheathing in coil-pack harness wiring

While changing spark plugs on our 2013 XC70 T6, I inspected the coil-pack wiring and found two places where the jacketing was splitting open. The copper wire was still shiny orange, so I decided it would be best to just put a blob of superglue (cyanoacrylate) on the splits to seal the jacketing and prevent mechanical bending.

Is this type of glue OK for contact with copper?

Do people inspect the coil-pack wiring when changing plugs? Anyone else seen these signs of harness aging? On a 6-year old car?