Looks absolutely natural.
maybe if you just doubled up on the material you are using around the center of the buckle? Yes, I agree that the kit with the leather looks too thick. Even if you don't change it, no one is going to say "The buckles on the hood ruin the look of the model".. LOL Your work is absolutely beautiful !!!You have a good eye! The difficulty is to find a thin enough material that will look ok at scale and has a little bit of strench to it. I have the thin part but not the strench part of it. I tried thin glove leather but like every other builds I see that uses leather, it just doesn't look right. So it's all a question of compromise between having a strap that looks ok at scale and having a buckel that is not quite right. Here is a picture of a 1/8 scale model from Amalgam models that is close to 23k$ and that has, to my eye, a much too thick strap.
View attachment 428026
Finished the hood straps today. I'll let the radiator cover dry for a couple more days before handling it. So the front end should be pretty much done by the end of the weekend. I also installed the foot step. Next up will be the 4 fenders. I still have the wheels to finish but that can be done just about at any time.