I have been reviewing a Reader written completely in Spanish. The transcriber used Method 3 of the Interim Foreign Language Guide. I have come across a definition in the glossary that has a macron over an o in the word persone.
The text reads,
personal La palabra persona proviene de la palabra latina persone.
Obviously, the reference is to the macron in Latin. Repeatedly in the rules it says if you are working using foreign language codes, do NOT hybridize.
So sorry for the delayed response, but I will endeavor to answer. There is no official document for Latin braille alphabet and signs. It is the general belief that the intent behind the prohibition on hybridizing is for the main foreign language. As the Latin here is the secondary language, it is acceptable to use the UEB macron before the "o" in "persone".
The rules are trying to prevent the transcriber from combining UEB letter modifiers and foreign language code sign in a single language such as Spanish.