My understanding is that owners can only be signed up to a common property by-law with active consent – i.e. they sign the documents – unless the owners corp takes a reasonable proposal to the Tribunal and asks them to force it’s acceptance.
What the owner should remember is that if they had told the strata committee about this work, they would have been required to agree to a by-law accepting responsibility for the future maintenance of the tiles and waterproofing in any case. This is standard practice.
A reasonable by-law would be that the owners agrees to maintain and repair the tiles and waterproofing should they fail at at any time. An unreasonable by-law might expect them to take responsibility for the structure of the balcony and balustrade an I would be astonished if this is what the strata manager was demanding
The owner is well within their rights to reject any by-law that is not fair and reasonable, but they do have to take responsibility for the work that they’ve done without prior permission.
None of this will affect the saleability of the unit, unless the owner or Owners Corp refuses to agree to reasonable requests which, in any case, would be easily dealt with at a Tribunal.