To view flac files in the media browser, enable "Show All Files and Folders" in the media tab menu Views.
Although I would recommend loading sfz files instead of individual audio files.
The files are also visible in the DR multisamples dialog. It is possible to shorten the navigation to the SD2/SD3 kit pieces with directory junctions. I created a User directory in "Cakewalk Content\Drum Replacer" and added directory junctions to the two kits folders. Here is an example using default file locations for SD3. Run cmd.exe as administrator and type:
mklink /j "C:\Cakewalk Content\Drum Replacer\User\SD3Kits" "C:\Program Files\Cakewalk\Vstplugins\Session Drummer 3\Contents\Kits" It might be handy if DR sfz menu was expanded to include SD2/SD3 kit pieces.