As for your issue, telnoi, I am not sure that the problem is in Corona (but it doesn't mean it can't be!)...
I tried your scene and could not find good settings for the displacement effect, indeed. Actually, the model looked best without the displacement. I then tried to verify the displacement is working by making a black-to-white gradient and applying it to one side of a 5cm large cube. I added another 5cm cube for scale. The gradient was then used as displacement with min value 0 and max value 5 and by looking at the other cube, I could see that the displacement is working as expected. See the attached image.
I even verified the normals to make sure that the problem doesn't lie there. But they were all looking as expected.
I am sorry I cannot help you more at the moment, but to be able to debug the issue (if there is any), we'd need a more simple scene than a chair with super-tiny displacement, which is not easily quantifiable. If you could make such a simple scene in the software, from which the chair model originates, that would be much better.