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 "The UV´s have much more padding now, but it still has shown the same issues (second image)"

Hello,

Your problem is related to UVs, but not to padding. And it's not even a problem with the UVs themselves ; you are witnessing (and currently misinterpreting) a rendering error and attibuting it to your normalmap or your UVs even though they're not the culprit.

You need to understand that the colors of a Tangent Space normalmap depend on UV orientation. To visualize this, set your current asset aside and focus on something much more simple, like a simple crate or some random blob sculpt. Make a lowpoly for it, give it some UVs, and bake it. Then make a few other other bakes, each time rotating some of the UV islands at random.

You'll notice that even though there are color "jumps" at the seams, and also different colors depending on the various test bakes at different UV orientations, this doesn't mean that things shade badly (if your renderer is setup correctly of course). Many people new to this fail to understand this specific aspect of tangent space normalmaps.

Now if you do have a shading breakage at the seams when just displaying the shaded normalmap, this just means that your renderer is setup incorrectly. But that doesn't mean that your baked normalmap is incorrect.

And beyond that, if you use any sort of trickery to generate other passes based on the 2D normalmap ... then of course you'll get seams there too. But that isn't the fault of the normalmap either.

Bottom line : for now, only focus on a very simple asset and only worry about the shaded look with the normalmap alone. Try the aforementionned tests, and you'll understand.

(As a side note your asset has way too many seams. While this is not the root cause of your issue, this is asking for trouble and should be avoided because even though a renderer will shade smoothly across them, it will only do so up to certain mip level. So if you want your asset to behave as well as possible you should minimize them.)

I would recommend doing as Pior suggested. Make a simple box with rounded corners, this will be your high poly. Make a simple box with only 8 vertices, this will be your low poly. Then test your whole baking and rendering pipeline, and work on resolving your problems. The simpler model will make it easier to isolate problems, and fix them.