I would not assume that my attempt to translate neumatic notation into modern music would be correct. From your description, I am guessing that all of what you are seeing is conventional understanding of Gregorian chant notation, observing the practice in use before the 1962-65 Vatican Council. There is no official braille equivalent, since scholars cannot agree on its meaning. I suggest you use the table from the front of one of the editions of the Kyriale (a small book) or the Liber Usualis (a big book), both of which are available in most libraries. A TN that the notation has been translated to equivalent music notation and naming your source is, of course, absolutely necessary. As with many other notations, it would be entirely appropriate for you to dodge the issue and simply say that the examples do not have braille equivalents. I have been told that attempts at tactile graphics are not very helpful.
Good to hear from you. Keep up your good work!