I won't disagree with your assessment of the picture quality - the grinding looks pretty good to me.
A horizontal surface grinder usually (always?) has the grinding wheels mounted on an arbour with facility for balancing.
The wheel being out of balance is probably the cause of the slight ripple.
Your table drive arrangement is very different to my Union (I'm not sure it's a Union but it may be a clone - there are no markings that I can find.)
One job on my 'to do' list is to make a surface grinder and I was going to use a timing belt drive for the traverse.
Good luck with your HPC enquiry.