An "enrolled agent" is generally not a CPA or attorney; neither a CPA nor an attorney need or benefit from "enrolled agent" registration, and in practice either would lose status from such registration.

To address the boldface above:

(1) No, "everything at withdrawal" is not taxable by the US, so unless you have a passionate desire to contribute to the federal deficit......??

(2) No, withdrawals of the employee contributions are not taxable, ever, since (as I wrote earlier) they were from after-tax income (to the US). (Did you mean to write "employer" contributions? They aren't reportable on withdrawal either, since they should have been reported & taxed on contribution.)

(3) The employer's contribution should have been reported when made, but if you wish to argue "no", then yes, on withdrawal you could elect to report that amount plus interest. I would never do that, but it is an option.

From what you wrote, you should have reported the employer contributions as income in the year they were made, but perhaps you did not. That does not mean you owe US tax (the tax credit for CH taxes, and the earned income exclusion, each apply). So, either review this with your tax advisor, or just ignore it.

Do the arithmetic, and compare the tax you would pay to CH if you withdraw the pension this year (as CH tax residents) with the tax you would pay to the US if you withdraw next year (as US tax residents).