The members of the cataloguing team were looking for a collective name for themselves as a group of people.
In our mind the Cataloguing Cadre is a small group of people specially trained to carry out a particular purpose, which in this case was cataloguing the Society Library books.
They are the 'Fundi' of cataloguing our books. Fundi is Swahili for an expert, specialist or craftsman.
Those of a military bent a Cadre is a complement of officers of a regiment (1851 OEDOHP) and list of such officers (1864 OEDOHP).
OEDOHP is the Oxford English Dictionary on Historic Principles.