NRF with multiple transmitters - IMU units

You will have to change the hardware settings to your setup.
My setup uses a more standard connection (IO shield/Joystick shield).

RF24 radio(9, 8 ); //CE, CSN pins

Was your setting IIRC.

There should be output at the tx station on failure.
The rx should print all ten seconds "10 seconds silence" on failure.