In all honesty i think that the veil is the thin but definite separation of the world of the living and the world of the dead. I don't think the the spelling has anything to do with it... But knowing J.K. it surely could. Maybe she is trying to say that anyone who tries to find out what's on the other side of the veil is doing something evil. Basically another way of saying, live your life and enjoy it now?

I think the reason
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serius died
was the fact that he crossed through the boundry. It's just not something that's supposed to be done. And when you think about it, in the entire series, she is basically promoting the thought of accepting death for what it is
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with the deathly hallows and "the true master of death doesn't fear it" type of stuff