Why does the CEB alternatively translate and transliterate "Satan?"

I understand that the word Satan refers to a Biblical character and can be literally translated as "accuser" or "adversary," but I would expect a translation to choose one interpretation and stick with it.

In Job, the word is translated into "the Adversary."

In Matthew 6:23 and Revelation 2:9, it's transliterated as "Satan."

Does this reflect a distinction in scholarship? Is there a major difference in the ways that the Old and New Testaments use the word?