But Japan in the 1910s is much different from Japan of the 1930s. In fact, stronger relations with Japan, and it being more recognized at Versailles, as well as butterflies causing it to focus more on technology could lead to a stronger army with more of a chance of global projection....perhaps actually becoming a threat to the US, but in this scenario, equally possible that they might become cordial with each other.
And remember, the foresight wasn't the same as today. Economists predicted Japan would pass Britain economically by the end of the century, and it did, but from their POV, wouldn't that look like Japan passing the British Empire economically? And thus being a potentially better ally than the fledgling US? Granted, I don't know why it becomes one over the other in these situations....it certainly doesn't have to be the case.
On another note, Japan could perhaps also decide to go north, and fight in Russia during the Civil War.....