Coco contains a lot of K and holds onto Mg and Ca, that has an effect on PH and EC run off which is why you don't chase your tail by trying to sort out the run off ph. The most important things are the PH going in and having a reasonable run off which stops salts building up, combined that allows roots to absorb nutrients and avoid lock outs.
Cant do much about the castings either, obviously that's going to affect ph coming out . You cant take them out so no point worrying, you could reduce nutrients on those pots if they start causing problems.
You should see a steady improvement now your getting more run off though.
