I think it's mostly when you compare the trailers that the voice acting seems better in Japan. The trailers are made originally for the Japanese version of the games and so they take the lines that sound very well done in the Japanese versions and use them in the trailer. Unfortunately, if that scene is not as good in the English version (in this trailer, most notably Leon), it's still thrown into the English trailer instead of them opting out for different lines.
okay now i must say:
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