Another one Mitch,
https://history.state.gov/historicaldocuments/frus1961-63v04/d47
CIA report on Nhu.
When unclassified point 1. might read;
""so and so" is surprised that this is news to the US since it was reported months ago that Nhu has been up to no good"...
Of the hundreds, if not thousands, of telegrams and other messages sent between the beginning of the Bhuddist crisis and the November coup, you've found two they you think indicate that Nhu intended to throw the US out and make peace with Hanoi. There's another cable that was sent to Saigon in response to the May cable, which ups the total to three. Compare those three to all the cables involving the various forms of hand-wringing over the GVN's handling of the Bhuddist crisis over the same period.
BTW, if you take doc 47 at face value, it doesn't help you. If the US didn't know that the French ambassador was acting as an in-between for Nhu and Hanoi at the beginning of September, then they didn't know in mid-to-late August when the decision to back a coup was being firmed up. It couldn't have had any influence on the US decision in that case.
One telex further down the line:
https://history.state.gov/historicaldocuments/frus1961-63v04/d48This is an account of what Nhu told an assemblage of ARVN generals on Aug 30, essentially spelling the end of the August coup plot.
In the message, one of the things Nhu tells the generals is, "I know without American aid we cannot exist. USG is only country willing support our country without any strings attached."