Have you fitted the Wunderlich part? It does not include the lead and it appears to tell you you need a leadWunderlich also has a specific GPS relocation solution, different from moto-mate: wunderlich rs1300 gps relocation
BMW (61125B4E229 I’m curious to know if is a replacement ( longer lead ) or an extension for the original.I have the moto-mate fitted to my RS. I extended the original lead to re locate the mount rather than take the bike to bits. The mount in my user opinion isn’t at the best angle and depending on the road ( possibly engine vibration) it does vibrate. The location is much better than the original but it could be better.