@cpasjuste Ive just noticed a bug or it could be something else but I copied the same setup on another 3ds but this one had 10 dsiware games on system NAND and it wouldn't boot it kept freezing on selection screen I tried different things to boot and checked config but it was definitely related to the dsi games. As soon as I deleted them it booted fine. This may have something to do with dsi game apps running in the background. I just thought I'd let you know, it's not a major problem and not sure if there's a fix anyway.
-edit just been replicating this problem I installed 1 after another dsi titles and everything was fine up to 5 dsi titles then after the 6 install no longer booting on menu. I removed 6 dsi game and everything booting again. 5 is working still. So with a certain amount of dsi titles there's a problem booting. This on a old 3ds and may not be an issue on new 3ds. Maybe ram related issue due to animated icons and not static ones. Probably why Nintendo didn't use animated icons for the 3ds. Anyway thanks the themes feature is excellent.