I upped a lot my Mg to match EI level, not sure why aquariumplantfood.co.uk recipe is so broken. No K2S04 and Mg dosage is so low in it.There is yet another thing which came to my mind: whenever I see curled/twisted leaves or stems I look at the levels of Ca/K/Mg - these three ingredients (plus tiny bit of Chloride) are responsible for the pressure within the plants tissue so this may be the case as well - but you'll need to achieve correct levels experimentally. I personally keep approx 4:1 Ca:Mg and then fine tune K.
After increased dosage my plants starting to look better even after a day. Will post after week, how is going.