The multiplex unit is part of the under-dash fuse box. There are YouTube videos about it for Civics and Gen3 CR-Vs, but not Gen2. Just search Honda CR-V multiplex .

Troubleshooting tips (no pics)

Multiplex Control Unit Input Test | Honda CR-V 2G 2002-2005 DIY Repair Guide

 

50 milliamps is about right for almost any vehicle.
There are certain circuit that need to be powered up, even with the car parked and turned off.
This is part of the reason why vehicles need to be started and run for a little while
Can not be left standing un-used for long periods of time.

Power is used by the radio keep memory alive circuit to maintain radio pre-selection
Clocks, ECM, PCM, body control module, etc. need power to keep memory alive.
(fuel trim data, TPS data, DTCs, Freeze frame, etc.)

 

Six tenths of a watt shouldn't be an issue if your battery is in the full bloom of health.

 

Have you managed to find the fault Matt?
Im having the same problem with my 2nd gen Honda - battery drain around 40mA from a circuit behind fuse 9. 40mA shouldnt kill my battery but it does overnight - i suspect that 40mA must periodically spike overnight.