El Quijote universal : 150 traducciones en el IV Centenario de la muerte de Miguel de Cervantes / editado por José Manuel Lucía Megías. (OCLC #985966961)
The OCLC Bib Formats documentation says for field 041:
For works in multiple languages, the codes for the languages are recorded in the order of their predominance. If predominance cannot be determined, record the codes in English alphabetical order. If the code mul (Multiple languages) is recorded in Lang (meaning the item is multilingual with no predominant language), the code for the title (or the first title, if there are more than one) and the code mul are recorded. Alternatively, any number of specific language codes may be recorded in repeating occurrences of subfield ǂa.
The first option is used for this book:
Lang: spa 041 1_ ǂa spa ǂa mul ǂh spa
So where to draw the line? How many languages are too many to list? This decision may vary by institution; for example, National Library of Medicine used the mul code for titles in more than six languages. I don’t know that my library has a limit for how many languages we will list, but with translations in 150 languages, mul seems far more reasonable!