In the English-speaking world, the King James bible transliteration of the name of God as "Jehovah" has been more familiar to English-speakers for centuries, than the transliterated "Yahweh". (I'm not certain, but I believe that even the "unofficial" English-language bibles which preceded the KJV also used "Jehovah".)
Just a guess, but this may perhaps be why the most common male English first name is spelled "John" and not "Yohn" -- or even in the Latin form of "Ioannes".
But yes, you're quite right, Jon. "Yahweh" is the correctly transliterated Hebrew rendering.
Here's a gold star for you. * Sorry we can't give you any schoolroom awards for good manners, though.