MP, best hand South, Instant, pro GIB 30.
I don't see that South's bidding contributed to E/W result. They did that all on their own.
It may not be possible to construct a hand for South where 3C is consistent with the earlier 1N, so I grant that this may have been a confusing/influencing factor (although GIB does provide a definition for 3C, so perhaps the possibility is not outlandish).
The explanation for 2S includes 4+ Spades. I think it should be 5+ (and usually 6), and West will not feel constained to insist on H.
4S makes but I don't think that East has game ambitions when bidding 2S. West it seems thinks that he did.
BTW, had you been East, would you have left the 4HX?

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ing) tr. v. - Any bid made by bridge player with which partner disagrees.