According to OGM, "[Our LED] navigation lights are tested by an independent USCG approved testing laboratory. The lights are engraved with the USCG specification that it meets. For example, our 2 Nautical Mile visible lights are marked with USCG 2NM."
So, while the USCG does NOT do the testing, there is a USCG Approved lab that does.
If the responsibility for an incident were being assessed and you were using a NAV LED, properly installed, in an application for which it was approved and bore the USCG specification for that application, it seems that the manufacturer would have some skin in the game, and probably have their lawyer involved defending YOU.