Back in 2020, I pointed out there are undeciphered letters from Philip II to Juan de Vargas Mexia, his ambassador in France, and identified four ciphers used therein (see "Finding the Keys to Philip II's Cipher Letters to Juan de Vargas Mexia").
While re-reading Leader (1880), Mary Queen of Scots in captivity some weeks ago, I noticed Vargas Mexia's letters are printed in Teulet (1862). Now I could have the time to check it and confirmed the letters in BnF es. 132 are not printed in Teulet. (My comparison was based on the dates and correspondents. Although I found two letters with the matching dates and correspondents, the contents do not seem to match.)
I also found further undeciphered letters from Vargas Mexia are catalogued in BL Add MS 28421.
I added these under the section "(Additional Note, 23 June 2024)."
