That's interesting. I recently got about eight or ten cubic feet of rippled black walnut, it's not that common in the US let alone in Europe, so it's quite a co-incidence that we're both dealing with this wood at the same time.
I planed the board in the photo and a couple of others. I put fresh knives in my planer/thicknesser and it planed very cleanly with no tear out. And there were no problems planing it by hand with a 50 degree frog and a sharp iron. I've also taken some saw cut veneer from it at just under 3mm thickness and again it was very well behaved on the bandsaw, I then took it down to about 1.8mm on the drum sander with 80 grit paper, I'll finish it down to about 1.5mm with finer grits on an orbital sander. So far it's staying flat, the edges are easy to shoot, and you couldn't ask for a better mannered piece of wood!
I expected to have to use a special set of planer/thicknesser knives that I keep with a ten degree back bevel, plus a bevel up plane set at a 65 degree angle, these are what I often use on heavily figured timbers, but so far none of that has been necessary. Sharp tools and fine cuts have been all that's required.
I've also been working my through a number of projects recently that used equally heavily rippled English Walnut, and that was also fairly straight forward, it needed a little bit of scraping around some feather figure but quite a bit less than I often have to deal with on other timbers. Walnut, as long as it's not out and out burr, is a pretty accommodating timber, so if you're having problems it's likely to be something simple like your tools just aren't sharp enough.
Good luck!
