Minor problems:
The file is named JKSM but the directory it creates is named JKSV.
When I look at system titles, I see a ???. It has high 00040100 and low 00021a00, and is CTR-N-HCBE. Searching for this shows that it is the system transfer application.
Also, I was trying to use this to transfer Streetpass Mii Plaza. Being able to transfer system titles makes it almost work. If I transfer all of system, extdata, and boss, for both Mii Plaza and Miimaker (to get the CFL_DB.dat), game progress is correct, and number of streetpasses is correct.
However:
1) Plaza population is slightly too high
2) All Plaza inhabitants are listed as having been tagged a minute ago
3) Most inhabitants do not have a last used software. I noticed that inhabitants that used Pokemon OR or system applications did still have the last used software. It so happens these are things I have played on this machine (which was never used much).
4) I had some miis I hadn't played with completely (since I hadn't used them in Find Mii). I also had some I had just met. Neither of these showed up.
Does anyone know exactly what I need to copy, and if I need to copy something else? #1 and #2 make me suspicious that the CFL_DB.dat just adds to the existing Mii database and the actual database is something else. Attempting to fix #3, I copied Activity Log system save data, but the result was an activity log which resembled the one on my old machine but with blank spaces for titles I hadn't played on the new one.