@warblade52
.System folder on the card won't work at all. Much of what you've mentioned will work in a Garmin root folder on the card though. Any language-specific *.srd files need to remain on the unit in .System/ASR because they cannot work from the card, but the map-related *.asr and *.srx files can go in sd:/Garmin/ASR.

@kilgore
Search will not be fully functional for EUU in 169x or any other 1xxx device, but results may vary depending of how and where you search. The map Garmin supplies for your 1690 is the non-unicode EU.