Usually a buffalo sauce is made with a bottle of Franks or something of that nature. I have found with all the many options of easy in the bottle buffalo sauce, Franks is the most mild. There are a couple of options I do to tone it down.
This brand makes a "wing" sauce that is not as hot as the sauce, however I do not like the after taste...
I like to dilute the sauce with some unsalted butter, I know not the healthiest option, but sure darn good.
Another way to create a buffalo sauce is to add a little sweet essence to it, a touch of BBQ sauce, the sweet will counter balance the spice.
That is the main idea, spicy will tone down with a little sweet or sour additive, so use your palette's preference. Hope this helps!