Whether B.________ could validly represent W.________ before the appellate court
No. The cantonal exception allowing non-lawyer representation in contravention matters applies only before administrative contravention authorities, not before courts; the appeal was therefore filed by an unauthorized representative.
Art. 127 para. 5 CPP reserves criminal defence to lawyers entitled to appear before courts. Art. 21 LVCPP, by its wording and legislative history, is limited to prefectural administrative authorities. An insurer acting under a power of attorney cannot replace a qualified lawyer before the court.