I would like to know whether R24 has been correctly applied to pulldown the EN pin when none of the diodes are switched on.
The idea here is that voltages higher than 3.3V may be applied from any of 3 sources to bring the EN pin high. The zener forces these voltages down to the maximum pin tolerance (3.3V). When none of the diodes are switched on, the EN pin must be held low.
Alternatively I could put a high value pulldown in parallel with the zener.
Edit: A high level requires 1.7V and low less then 0.5V. Pin leakage current is 20nA. Input voltages range from 3.3V to 5V when active otherwise float.