I guess the lack of a single standard definition for the term 'completion' is part of the problem. Buildings may meet agreed criteria to be 'substantially complete' from a contract perspective, triggering payment obligations between the parties - yet still have material amounts of work tob e done. In a condominium building, items such as amenity areas, final finishes in lobbies and corridors, missing items in units, and so on will not stop a building from receiving occupancy permits or being occupied. I was using the word 'complete' in a general sense - the City does not decide when a builder has met all the requirements to have a fully completed, no items remaining status for the building, and does not take that into consideration for registration. The focus for the City would be on approvals and completion of requirements over which it has authority - site plan approval, meeting conditions stipulated in the various permits and permissions issued and granted by the City.
The condominium corporation is created when the City files the necessary registration documents on the Ontario Land Registry system , which causes the individual physical condominium units in the building to become separately titled entities within the land registry system, with the ability of the titles to be transferred to the new owners on closing. Absolutely nothing to do with completion of the common areas - the amenities, finishes in the lobbies and corridors and so on. The title is for the unit, and as a condominium, includes its proportionate share in the condominium corporation's assets (and obligations), including its common elements and amenities.
Toronto has registered thousands of condominium corporations over the years - obviously, they have defined procedures, internal checklists, of what must be in place for the entry to be set up in the land registry system. It is up to the developer to prepare, submit, and revise where necessary, all the documentation required by the City. Does the City have an openly published list of what these requirements are - that I do not know. If there is a list, it may be either within the City's legal procedures and regulations - possibly in several places, or it is in internal development industry papers.
I think the bigger issue is that neither party - the developer or the City - can predict or control how long the other party will take to complete all its outstanding issues and requirements for the registration to proceed. Without that knowledge, neither party is willing to make any commitments in advance on when the registration will take place - hence leading to the situation in which purchasers are left hanging.
As to why some properties register more quickly than others - developer experience would be a major factor. Also, a greenfield project would be a lot more straight forward than one in which the developer had to go through hoops to get approval in the first place. Incorporation of pre-existing structures - whether historic buildings in part, or conversions of office buildings or churches, or other commitments to the City for approval to build (e.g. replacement of former rental units on the site).
The above was written without thinking about which building you are in - just looked at the thread title - the Waterworks building. Oh my. This site has amongst the most potential complicating factors for approval around. Be thankful that it is a Mod project - Mod has experience handling complex sites. In the hands of a developer without such experience, it could be a much different situation.