There's not really an easy way to identify them unless you actually know anything about Pokemon and Pokemon cards to begin with.
The thing to note is, Japanese language cards are generally worth their most when they're *in* Japan. There's just not a lot of demand in the English-speaking world for Japanese cards among those who do collect Pokemon cards, *especially* newer cards, because those who play the Pokemon Trading Card Game in the US, Canada, Australia, New Zealand, and the UK can only use English-language cards. Chances are you'll lose money and you'd have probably been better off giving that cash you spent on the cards straight to the charity instead.
All that said, I do know enough about the cards to identify them but valuations will generally not be what you're expecting them to be.
