I'm interested in finding out how the Japanese reacted to the Navajo code in WW2. Were they aware that it was a Native American language? Were they close to cracking the code? All the resources I've found about the use of Navajo code are usually US based and give a US perspective. I'd really like to see a Japanese POV on it.
There will be more to say, but this question has prompted a couple of interesting threads here before, and you might like to review those discussions while you wait for fresh answers to your query:
How hard it was for WW2 Japanese to decypher Navajo language (code)? with u/When_Ducks_Attack
How did the Japanese not figure out the Navajo Codetalkers in WWII? What did they think it was? with u/hatari_bwana
How far did WWII Japan get in trying to crack the Navajo code?, with u/chalkfarmer