I was talking with a friend yesterday about Sunday's session and she said, 'The clue is in the name'. Which indeed it is but only if you use the correct legal terms. When people use the term building trustee they are (a) not using the correct term and (b) leading some people to believe that they have responsibilities towards the building - which often they don't.
So perhaps the first action after reading through your governing document a few times is to ensure that roles have the correct names. A holding trustee is an individual who only 'holds' the title to the property. A custodian trustee, which is an incorporated body (i.e. a company) only has custody of the building. That is it unless they are given other responsibilities by the governing document which is why you need to have read it.
Action planning still to come.