If you have the key, I wouldn't worry about it overmuch. I got the email from the FastSpring folks, and they should fix your email address (I'm not sure that I can directly alter order details). If I'm misunderstanding and you don't yet have the key, please let me know and I'll send it to you.
Hopefully that email address that was the typo doesn't exist and thus the key wouldn't be shared with someone random. But if you run into any such issues such as registering the key with Steam, get in contact with me and I can get you a replacement since you bought direct from us. My main recommendation would be for your friend to register that key on Steam as soon as possible if they are intending to; and if not, there's really no issue, as we don't have any sort of server side checking of keys or anything like that.
Hope that helps!