Is money earned from engineering supervision contracts permissible, knowing that the engineer does not perform actual work, and it is a condition for registration not to be a government employee? Is this money considered dubious and must it be returned?

The salary for thefirst year is permissible, because you are a private employee who is entitled to wages by dedicating yourself to work, whether work is available or not. As for the salary for the second year, it is not permissible for you to take it as long as you are employed in another job and renewed your registration with the syndicate deceitfully. You must return it to the employer unless he willingly relinquishes it and gifts it to you.