Dimitry,

>>mahaamoggallaanatthero assa kammavaacaacariyo ahosi.<<
>>his instructor in ways of action (?) was Mahamoggalana Thera.<<

A kammavaacaacariya is someone who teaches the proper ways of doing the
formal acts of the Sangha (i.e. the verbal 'announcements' that accompany
these acts). There are many in the vinaya books.

Sean