You can find the register file relatively easily because it's a block of memory that's the same on each core but isn't cache, but it isn't a 1:1 map from architectural registers that we would recognize: the chip is designed to find an optimal allocation of slots in the register file to runtime values.
These particular registers aren't part of the CPU proper anyway, so not in the register file in that sense -- they're mmio mapped, and https://securelist.com/operation-triangulation-the-last-hard... concludes that they are "a block of CoreSight MMIO debug registers for the GPU coprocessor".
