The culprit is this:
"boundary_encoded_points_string":"kfqwFzkwbM}uAwM_iAmIgi@yQyfDm{BqmGc`Eon@ki@ir@{Ogt@cCcSia@{t@e`@}k@}Lwi@k[qBe[~Fc]lI}KzEcO^aUxFgN~I{Gd]pEff@xe@ra@h[pz@tj@hjA~b@loAoFfhAdAdf@ea@jk@{@vc@hh@dk@~[pb@lEfX_HtQ|CjWzWv|@vp@nh@vj@bYde@bf@dOri@Hvn@wBvtAtf@rS|y@zEzfA|Ofa@te@~|@{B|o@_Wd\\}n@s@"
remove the double backslashes \\ nearing the end.