1) Where is the Ischia?
I removed the IDY and calculated 50gr of Ischia, but it was not enough. Last night we added 100gr, so we will see what happens.
2) Balling a dough 3 hours before use may not be the best idea.
This is still an area I do not understand. The only argument I have heard for having dough balls rise over a long period of time is - tenderness. However, in my experience, I get less oven spring from dough balls that are older than 6 hours.
3) Brown sugar may be a little out of place too
Based on info from this forum - I have heard both that adding a little sugar will help coloring - and that is will hinder it.
1) 50gr is about 2% of your formula. If your fridge temperatures are correct it seems like you put together a good formula. Although 14°C to 18°C (57.2 F to 64.4 F) is a pretty wide temperature range and according to the Sourdough starter quantity predictive model, your fermentation time would be between 85 and 45 hours. Maybe you were under-fermented? How sure are you of your temperatures?
2) I'm assuming you are re-balling and allowing to rise at room temperature, not in the fridge right?
3) My sugar comment was really intended for true Neapolitan, but if you're doing a NY/Neo hybrid it's not really as relevant. Although I'm suspicious of mixing Ischia & sugar.
I think you are on the right track, your current pizza looks very nice. I just don't want you to give up on Ischia because of "lack of flavor", which to me is a red flag on your process. In my opinion I think you are just using an under-fermented dough (which I think you have the same hunch since you doubled the Ischia %). Once you get the right fermentation you should see an improvement in crumb & flavor.