They partially are, for a few reasons.
The original Unity pack has most of the block textures already done and I've simply recolored them/shined/bolted to fit GT materials. The machine faces (some) are heavily edited Unity TE textures, (ore washing, furnace/smelter) which are already based on TE anyway. The machine input/outputs are DIRECTLY inspired by TE. Things like the Laser Engraver are built from the ground up.
I thought CyanideX's TE style looks great for GT and it clearly shows you what each thing is doing. Big red or green rings around I/O, drains, etc.
The items are mostly original from myself build and textured pixel by pixel from the ground up, though. Some are edited but most are unique to this pack (or my old painterly FTB work).