Sorry to say it "fli" but the recording has pilot error written all over it.
Wrong read-back of cleared level.
Query from ATC as to passing current level and standby for further descent after passing the Air Seychelles at FL 370.
Didn't they see the TCAS inbound threat and wonder why the traffic was becoming a likely threat and not query it?
(It worries me in the transcript that Mauritius ATC was willing to "drop" the incident if Air Seychelles was).
Just a few observations from the crewroom bar here.
Stay safe, everyone is watching YOU!!
J