It has a lot more than two extra cores. The IO alone is 10 cores worth and Tempest is pretty much the power of Cell.
You are don't follow me, you cannot just compare how much equivalent each IO system and then said (If I understand you correctly) PS5 has works
in IRL like it has 2 core more because one system needs a much better IO for three basic reasons:
1)Has more raw bandwidth so much data needs to be streamed and decompress.
2)The approach of stream directly to cache of GPU is great but until some dev with access to dev kit say a number compare to XSX you cannot just use number
which think is equivalent to that feature.
3)Yes PS5 focus in big part of its IO in remove footprint of the CPU, but the only thing we know now XSX use CPU is for example for access to the SSD as ram they
said 10% of a core (DirectStorage) and they cannot stream directly to the cache as we know so this also should be impact the CPU but just don't know how much
I am Sony sure will got a better sound compare to the XSX but again you cannot you make an extrapolation from that (Tempest similar to CPU of PS4) to say that in order to
get that sound XSX will use more cores, when in reality which will happens is the dev probably prefer its game has worst audio than take more CPU.
Something I want to know of XSXs is the sound how much will affect in performance the GPU.