Malone
You might well be right, in the crossword world, but I was thinking of legal English. I remember when I was studying Company Law that there was a case about "Cumulative Redeemable Preference Shares". It was held that an adjective qualifies all the items in the class of the noun. Thus all the Preference Shares were cumulative and also redeemable. Thus "overlong down answers" means that all the down answers are overlong.
We sometimes get "Across clues contain an aditional letter...." and this means they all do.
It is an interesting point. I dont know if a lawyer could advise us. If it is ambiguous, the setter could have said that some of the down clues were overlong.
By the way, I am glad you are back on EVs as I will need your help on this and others!