Is Jacobus really best translated "James"? Why not Jacob?

[Jayne]

But whether there is any typology going on, I have no idea. (I wasn't even aware of any typology involving the Judases until Xavier pointed it out...)

In general, typology is not especially obvious and occurs at a deeper level of Scripture study.  Also most types do not share a name with the person they prefigure.  Even if there were a good case that Jacob is an typological relationship with James, this is not an argument for changing the traditional translation of James to Jacob.

[aquinas138]

In 5 samples, I did not find any counter-examples.

I realized later that I had only checked European languages, so I looked at a Korean Bible.  It too made a distinction between the names:  ??  and ???  (pronounced /yakob/ and /yakobo/)

That's six for six.

Syriac is the only one I know that renders it the same in both testaments, ????? (ya'qub). Coptic, both Bohairic and Sahidic, as well as Classical Armenian use the Greek forms (more or less).