Since my first L322 model back in 2002, condensation in the various lights has been somewhat of an issue.  It has gotten better in the later years and here’s some info from TSB LTB00127/2008.  It focuses on 2008-2009 models but still gives you a good idea on what they consider too much/too little condensation and whether they will allow or deny a warranty replacement.

Headlight Summary:

Natural condensation under certain atmospheric conditions – normally a thin misting – within the headlamps.

• Incorrect replacement of bulb-covers following bulb replacement, or blockage of breather tubes, can lead to condensation forming. Ensure bulb-covers are correctly installed, and ensure that the breather tubes are not blocked and are free from dirt or debris. Clear the blockage or replace the breather tube if necessary. If this is determined to be the cause of the condensation, measures should be taken to dry out the lamps. Condensation levels should be monitored to allow natural dissipation of the condensation.

Cause: This is caused by air humidity condensing on the inner surfaces of the lamp lens, generally in colder weather. This will usually clear and exit through the breather tubes as the lamp heats up during a 30 minute period of normal dipped-beam operation. Suggested Customer Concern Code – L29.

Action: Always refer to the attached illustrations for guidance on acceptable misting conditions before proceeding with any repair. Should a customer express concern that after 30 minutes of normal dipped-beam operation, considerable water droplets remain on the inside of the headlamp glass, or there is evidence of standing water within the headlamp unit, the lamp should be replaced with a new unit. this bulletin has been issued to assist Authorized Repairers in providing a detailed explanation relating to Land Rover’s standards relating to this subject

Unacceptable Taillight Condensation:

Normal condensation is a natural process. Range Rover tail lamps are vented to alleviate changes in pressure through a breather vent. Atmospheric air contains water vapor referred to as humidity. When this air enters the tail lamp under any circumstance, there is a possibility that condensation can occur if the temperature is cold enough. When normal condensation occurs, a thin film of mist can form on the inside surface of the plastic lens. The thin mist will clear and exit through the vents during normal lamp operation.

During a period of normal tail and fog lamp operation (approximately thirty minutes) the condensation should dissipate as the lamp heats up.

However, if considerable water droplets still remain on the inside of the lamp lens after the 30 minutes of operation (Refer to the attached illustrations), the lamp should be renewed. If there is evidence of standing water within the lamp unit, the unit will also need to be renewed.

All illustrations below show unacceptable levels of water droplets