Section 5E. Notwithstanding the provisions of section 5C, the attorney general may elect to pursue its claim through any alternate remedy available to the attorney general, including any administrative proceeding, to determine a civil penalty. If any such alternate remedy is pursued in another proceeding, a relator shall have the same rights in such proceeding as said relator would have had if the action had continued under said section 5C. Any finding of fact or conclusion of law made in such other proceeding that has become final shall be conclusive on all parties to an action under sections 5B to 5O, inclusive. For purposes of this section, a finding or conclusion is final if it has been finally determined on appeal to the appropriate court of the commonwealth, if all time for filing such an appeal with respect to the finding or conclusion has expired, or if the finding or conclusion is not subject to judicial review.