I think the schedule of the AddToTmunu should be changed from
SCHEDULE GROUP AddToTmunu IN SetTmunu AFTER TmunuBase_SetTmunu
SCHEDULE GROUP AddToTmunu IN SetTmunu AFTER (TmunuBase_SetTmunu TmunuBase_ZeroTmunu)
since with support_old_CalcTmunu_mechanism=no, Tmunu is initialised by TmunuBase_ZeroTmunu and not by TmunuBase_SetTmunu. Otherwise, it could happen that thorns add to undefined value and afterwards Tmunu is set to zero. This did not happen to me yet, but probably only by luck.