The wall is stunning and creative, but sadly, I have to agree with the consensus expressed on all your threads: this wood should have been bone dry, carefully checked over piece by piece for holes, insects, existing fungus etc., and probably treated and certainly well sealed before before being installed. At this point, I would cut my losses and take it down. Once the pieces are all down, it's possible that if you thoroughly scrub off all fungus with a bleach solution, then let them dry bone dry (preferably in a wood kiln or perhaps a DIY drying shed), then treat and coat, these pieces could be reinstalled. Even that depends on the conditions they'll see - if this wall is exposed to lots of steam or grease you'll be having new issues before long. Also, is the wall itself dry and solid? Any chance water is leaking or oozing from somewhere and adding to the issue? What species of wood is this? Some species are naturally more fungus resistant and appropriate for this than others. Long story short, I'd recommend finding a different way to cover the wall - with ceramic, galvanized metal, or with a really scrub-resistant paint.

Fungus grows in warmth and moisture which is a good description of a kitchen. Mold could shut your restaurant down. Best to consult a mold abatement company.

You may have to take it down and start over. Pretty much you let your wood dry out one year for every inch of wood. you could take the pieces to a lumber yard and have them kiln dried. You don't want you diners exposed to mold and fungi. The carpenter helping you should have said something.

I just had mold removal on my new house because the contractor decided it was a good idea to wait until the end to put down plastic. They had to spray the mold and wire brush it. Then they treated the wood and sanded it. It wasn't a cheap job. It may be easiest and cheapest to start anew. I also recommend sinking the screws and filling the holes.