At least some of the songs are in CGDGCD, there is one song on a new youtube vid where he runs through the harmonics on the 7th and 12th frets and its def in that tuning. The use of the unison Bs is not obvious and by watching him in the vids it appears that the two high strings are more likely in C & D.
Also i figured out that heavenmetal is easier to play in CGDGCD and not CGDGBB, i don't see him using CGDGBB to play that song and he did play it live recently, also on youtube.
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