Is the money proposed by the lawyer in the form of his commissioning on behalf of the complex permissible or forbidden, and does the forbidden cease to apply if I participate with him in finding a solution to the case?

If empowering a lawyer to handle cases is not within the scope of your work, then there is no objection to taking a fee from him for that, provided that it does not harm the complex and that the cases are legitimate. However, if the company has authorized you to assign lawyers to these cases, then you are not permitted to take payment from them, because that is at the core of your work.