You thought Native Faith was hard? Try Necrofantasia's chorus lol...I usually get music done by ear, so if I'm ever trying to play something, it ends up being generic melody on right hand with arbitrary notes/chords on left hand. I don't know your level so I can't really help :\
Most touhou music is pretty good and some people say it all sounds the same. The vast majority can be rearranged on piano, they just sound a bit weaker because ZUN likes to mix it up a lot. Recently I've been listening mainly to 12.3's combined OST because it's the only one I'm really playing.
There's...
Mystic Oriental Love Consultation from, among other games, IaMP, which could probably be done easily as a soft arrange because it's a fairly simple melody,
Plain Asia from Touhou 8 where you can just play chords on left hand and melody phrase on right, ignoring the rest if you want (
this is a stylised arrange), and Evening Sky from SWR, of which there is already a good
piano arrange.
Plenty more, those are the ones I happen to like and remember are *relatively* simple.
Also, if you're following up on ciaza's green-highlighted song, search 'Beloved Tomboyish Girl' or 'Adventure of the Lovestruck Tomboy' (arrange), because, as always, he was a noob and just posted it in romaji.