You may have already found this article written by a vet:
Rimadyl: The Controversy | petMD
She writes about how lowered dosages of Rimadyl or alternative NSAIDs are prescribed for long term use when there is evidence of effect on the liver.
With Eddie's liver function values trending positively back toward the normal range, maybe lowering the dose and frequency more would be beneficial. It would also depend on whether the med would provide him the same benefit at those lower levels.