I agree with Old Man and Twisted. Very hard to understand that the Eibershter would give somebody a punishment for doing something which is not mentioned in the chumash or gemara. The mishna berurah writes in hilchos tefilin, I believe, that when kabalah contradicts gemara, we follow the gemara. Furthermore, he says even if there is an inyan mentioned in kabalah which is not contradicted by gemara, but somebody just does not want to follow it, we cannot force him.
Quite frankly, since we cannot fathom Hashem’s ways, we are probably best off doing those things we understand and that He told us about in chumash and gemara and which are brought down lhalacha. If I were before a human judge, and I decided to clasp my hands, and the judge put me in jail for 10 extra years, would that be justice? It would be a travesty. Unless one fully understands Hashem’s workings, it is hard to grasp these minhagim. If you are nervous, than keep them. If you believe that Hashem will be fair at all times based on what he wrote explicitly as the 613 mitzvos, then, maybe it is not important to worry about these hidden recommendations. Only if you are on the madraiga where you understand Hashem’s workings and how these minhagim actually work in the heavenly spheres would it seem proper to practice them. I for one am not on that level.
BTW, the Zohar also says one should never raise his hands over his head. Yet there is a picture in a well-known shul of Rav Shach giving a shmuess, where his hands are outstretched way above his head.