Three More Unsolved Letters of Catherine de Medicis, Charles IX, and Henry III

I was made aware of three undeciphered letters in the 1560s-1570s by Cipherbrain: one from Catherine de Medicis to Philibert du Croc, ambassador in Scotland (1567), one from Charles IX to Philibert du Croc, and one from Villeroi to Henry III (1577). I made references to these in "Unsolved Historical Ciphers" and "French ciphers during the Reigns of Charles IX and Henry III". 

Note (20 September 2021): The following is my preliminary assignment of symbols in Villeroi's letter. It was derived from the few plaintext written between the lines. It can recover some meaning text such as "tout cest" or "aurons tout", but I cannot yet derive further meaningful text from these.