Could Anal Gland Expression Raise Liver Enzymes?

It's very unlikely. Expressing anal glands is a routine, external procedure, and it wouldn't be expected to cause a liver problem weeks later, unless an infection developed and spread, which would usually cause obvious illness and a sore rear end first.

Liver enzymes can rise for many reasons, including liver inflammation or infection, hormone diseases such as Cushing's, some medications, and liver changes common in middle-aged and older dogs. It's good that he's acting normally. The recheck blood test will show whether treatment is working; if the values stay high, your vet may suggest an ultrasound or further tests to find the cause.

See dog anal glands.

This is general information, not a diagnosis. Please follow your own vet's advice.