I don't think it would be a side-effect unless correcting a deficiency encouraged new growth, which wouldn't be a bad side effect
It is true that an excess of one nutrient can cause a deficiency of another, but did you follow the iron label instructions? One thing I don't think we established was whether you applied the iron to the soil or the foliage?
The second leaf looks better than the first but still a bit stripey. I would still try the acid and water test poured around one or two plants (preferably ones that you haven't used the iron for if there are any) to see if the interveinal chlorosis improves beyond those that had just the iron.
As long as there is new growth that looks normal coming up within the flopped over central leaves I would not be concerned about the flopping. Keep checking them to see if they eventually straighten up. You may get more length and splaying out of the older leaves due to the amount of shade they're getting as well as the time of year although it's hard to compare your climate with mine. I would expect that if there was a serious problem you wouldn't have any doubts that something was wrong
