I'm going to try and be mildly helpful this time around and make a suggestion. The name Riku can be either Japanese or Finnish in origin. Neither Sora nor Kairi have any significant connections to any ethnicity besides Japanese.

That aside, I still stand by my previous belief (and that of many others). Trying to mix names with surnames of completely different origins ends up sounding ridiculous. I don't know what's so hard to understand or accept about that. Whether or not you're writing fan fiction based on the North American or Japanese release is entirely irrelevent. The names of the characters did not change in the translations except for slight romanization. I mean, had they changed Sora's name to Steve, Kairi's to Karen, and Riku's to Rick, then you'd have a good argument in your favor.

This is not the case, however, and Sora Abraham is going to sound terrible no matter the context.