3c & 3nt should probably also be limited to 2- spades. 3nt should show 5 hearts not 5-6 hearts most likely.
opener's 2s/3d should be 2- hearts. Don't really think that North should ever bid 4h over 3nt on this auction. It can try 3h with doubleton honor over 4c if it thinks the diamond stopper is too shaky and 4h plays better.

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