Aside from an English translation, are there any other requirements concerning non-English references cited in an IDS?

Yes. Applicant must also provide: "[a] concise explanation of the relevance, as it is presently understood by the individual designated in § 1.56(c) most knowledgeable about the content of the information, of each patent, publication, or other information listed that is not in the English language. The concise explanation may be either separate from applicant’s specification or incorporated therein." 37 C.F.R. 1.98(a)(3)(i).