[General]You have to add reversearrow.png and approachingcircle.png to your skin. If you want to have them in the original version just include the ones from the osu! template skin.
Taiko BGs are unrankable now. Taiko SBs are not unrankable. Your approach is the right direction but the order is mixed up. You should use a standard BG for your Taikos and use a TaikoBG as SB not the other way around. In your Taiko diff's .osu replace the Events block with this:
[Events]
//Background and Video events
0,0,"bg.jpg"
//Break Periods
//Storyboard Layer 0 (Background)
//Storyboard Layer 1 (Fail)
//Storyboard Layer 2 (Pass)
//Storyboard Layer 3 (Foreground)
Sprite,Foreground,Centre,"taikobg.jpg",320,240
M,0,-2000,0,320,240
S,0,0,100000,0.8
//Storyboard Sound Samples
//Background Colour Transformations
3,100,163,162,255
This way it is perfectly rankable right now. If you want to use this for future maps until Peppy fixes it client-side: Use your audio lead-in (here -2000) for the move command (or any other command that does nothing to the sprite) and set the ending of the scaling command to the end of your song (don't add to much length or you'll get the 'skip' button)
Edit: I already had a long chat with Ono today and he agrees to the changes. They are the only way to have a smooth workaround for the current "no taiko bgs" rule.
[Easy]KIAI should end on 01:26:432 - like in all the other diffs.
Contact me ingame or via forum PM after you've fixed the TaikoSB/BG and the KIAI in Easy.