In the case of CC-BY material, what should the license look like for a translation into another language?

We are translating a work of text that is licensed CC-BY, let's say CC-BY 4.0. The short version of the original attribution might be "CC-BY Smith and Jones".

We would like to license the translation as CC-BY also. How should we do this - how should we describe the license, in particular who are the license holders - are they both the original holders and the translators?

Your translation is considered Adapted Material.

Because the original work is CC BY 4.0, you are allowed to create Adapted Material as long as you follow the license terms. The conditions of the CC BY 4.0 license only include attribution, which means that your Adapted Material must retain certain elements, as defined in Section 3 of the CC BY 4.0 license - the identification of the creator(s), copyright notice, a reference to the CC BY 4.0 license, a disclaimer of warranties, the URI of or hyperlink to the original material, indication of modification (or, in your case, translation), and an indication that the original licensed material is under the CC BY 4.0 license, all of which can be offered "in any reasonable manner based on the medium, means, and context" in which you are offering the Adapted Material.

On their wiki, the Creative Commons gives some recommended practices for attribution. There are likely other ways to satisfy the license requirements, but this offers a demonstration of various types of attribution and how to ensure that you are following the license.

You can apply your chosen markings because CC BY doesn't require the Adapted Material under a specific license. Depending on the format, the Creative Commons also has a wiki page explaining how to mark your work with a CC license.

We were advised to simply add the translators to the CC-BY license, so that a translation into Chinese, say, might look like "CC-BY Chen, Wang, Smith, & Jones".

This looks consistent to me with the CC-BY 4.0 license specification in that a translation is Adapted Material and the only condition is the only condition of this license is to retain/provide Attribution to the original, which I suppose including the original names helps to do, although I think we should also link the original.

I'm not 100% sure that this is correct, and I don't know whether it is a standard approach. Would be nice to have a reference that endorses this more explicitly than the more unspecific writing in the actual CC-BY license specification.