trying to identify corner key and spline

Your photos are actually great! For the spline, see our 59-068. This isn't an exact match but it's similarly designed. We also have the 59-067. Carefully look over our dimensions and see what you think.

For the corner, there could actually be a lot of possibilities depending on your dimensions. Can you tell me the thickness and width of the legs? In the meantime, you can see our entire selection here.