Actually, the English runes are only used in THE HOBBIT. By the time we read the runes on Balin's tomb in LOTR, they're - well, not English any more. I remember being rather annoyed that I couldn't read the inscription.
I think what Tolkien said (elsewhere?) was that he only thought of Dwarves as Jews because of being scattered and having a language they only speak among themselves. In fact, if there's anything Semitic about the language, it's not Hebrew anyway, or even remotely Hebrew, unless you count the throaty sound of Kh, and there are other languages that have this sound.