I made it! We don't have dashi powder but do have dashi concentrate so I just put in a couple of drops.
My thoughts: celery juice is a pain in the butt to make (haul out the juicer for a small amount) and honestly doesn't come through here. This is quite delicious, however, like a fancy boozy limeade. The dashi broth works fine, I think a saline of sel gris would too. I'd like more mezcal (I used the good smooth one, though, so maybe it just needs the rougher one). If I make another round will increase the mezcal and celery. Oh, and "5 teaspoons" is a scant ounce, don't bother actually measuring it by spoonful. I do absolutely think this would be fantastic with stir fry or if you can get cel-ray soda where you are (it's not available around here) I think you could make something close and easier, the soda, soju, mezcal, dash of something sea-ish, adjust the acid.
Also it sounds like a lot of sweetener but this is not too sweet at all, and I often think standard recipes too sweet.