Thank you for posting your recipe, it is very insightful. If your SIP has been set up properly then you are in fact correct, watering should be 100% optimal and can be ruled out as the problem. Before I type anything else though, just know that you will definitely not lose your plant because of this. You are definitely going to get some good quality smoke, but your yields are likely to suffer unfortunately.
That being said, you have a lot more amendments in your soil than you need and it is pointing to excess K/Ca levels which appear to be locking out your Mg and P to a lesser extent. A handful of the ingredients in that soil mix are quite redundant unfortunately.
Your Crab Meal, OSF, and gypsum are all quite heavy in Calcium and that is likely causing your Mg lock out. On top of that, 1 1/3c Langbeinite is definitely overkill. Furthermore, the Dolomite Lime is pure Cal/Mg in a soil mix that already appears to be saturated with both. On top of that, you actually don't need Dolomite Lime if you use OSF because OSF has similar buffering power to Dolomite Lime. DL isn't bad by itself, but combine it with the Crab Meal, OSF, and gypsum and you'll lock out Mg for sure.
I hate to be the bearer of bad news, but at this point there really isn't much you can do but wait until you put new clones in. The term "cooking" soil is interesting to me, because it really is like cooking. When cooking, less is more. You can always add more salt to a meal, but you can not take salt out if you use too much. The same holds true for organic soil.
My advice for the short run if I were in your shoes, I'd simply stop feeding Cal/Mg+Lime and also make sure you don't add any more K to the mix either. I do, however recommend foliar feeding with Epsom Salts 100% at this point. I personally use between 1-2 tbsp per gallon of water if I find myself in this bind, and foliar feed is the most optimal way for the plants to absorb the epsom salts. Top dressing/watering it in is ineffective, as in this case the leaves actually absorb the epsom much more efficiently. Don't get too freaked out when you start seeing whitish spots/blotches on your leaves after a day or so, just what happens when the foliar dries up and is just residue from the salts.
As for my advice for the long term, look into Clackamas Coots soil mix. I've used it with great success, 1:1:1 ratio of peat/compost/aeration and only 1/2c Crab/Kelp/Neem meal per 1 cuft soil. Minerals would be 4c mineral mixture per 1 cuft soil, the 4c mineral mix should consist of 2.5c Basalt, .5c gypsum, and 1c OSF. Those handful of ingredients give your plant all they need. A note on P though, which will explain why you should remove Fish Meal from your mix. Too much P actually hinders the growth of microbes and will cause more harm than good. If for some reason you find yourself in need of more P, grab yourself a bottle of Fish Hydrolysate instead.
Simplicity works best here my friend. Always remember, less is more. You can always top dress more often, but you're SOL if you use too much and just have to let things ride. The issues you are having are quite minor in the grand scheme of things and are easily fixable. Research what I've just said on your own and draw your own conclusions, fact check me as I'm just some random guy on the internet
Hope this helped, and wish you all the best. Don't fret too much, your yields just aren't going to be what they should be but they'll still be more than decent and the smoke will be wonderful.
