Cuba is not listed in the Index to The Bluebook or in Table 2, Foreign Jurisdictions.
It is also missing from another frequently used source for non-U.S. legal citations, Guide to Foreign and International Legal Citations from New York University School of Law, Journal of Law and Politics.
The Guide to International Legal Research from the George Washington International Law Review (2013) does not provide Cuban legal citations per se, but it does include index entries for the Cuban constitution, current sources of legislation, news, treatises, etc., along with urls for materials which can be found online. Ask for the Guide at Research Services.
The Mabie Law Library has several Spanish-English legal dictionaries and wordbooks. Most are in the Reference Collection:
Dahl's law dictionary : Spanish-English/English-Spanish : an annotated legal dictionary, including authoritative definitions from codes, case law, statutes, legal writing, international treaties and legal opinions from attorneys general (2010; we also have earlier editions 2006, 1999, 1996, 1992)
Law Reference K52.S6 D33 2010
The ABA Spanish legal phrasebook, Ward and Cooper
Law Reference K52.S6 W37 2010
Aspen's English-Spanish, Spanish-English legal dictionary = Diccionario jurídico inglés-español, español-inglés Aspen, Kaplan et al.
Law Reference K52.S6 K36 2001
Teach yourself -- Legal Spanish: Bilingual Guide to the Legal Terminology and Laws of Latin America and Spain = Manual de terminologia juridica y legslacion de America Latina y Espana, Romanach
Law Reference K52 .S6 R65 1999
West's Spanish-English/English-Spanish law dictionary : translations of terms, phrases, and definitions of concepts of modern Spanish and English legal terminology, Solís et al.
Law Reference K52.S6 S65 1992
Butterworths Spanish/English legal dictionary = Diccionario jurídico español/inglés Butterworths, Cabanellas de las Cuevas and Hoague
Law Reference K52 .S6 C33 1991
Dictionary of legal terms : Spanish-English and English-Spanish, Robb et al.
Law Reference K52.S6 R62 1965