Since all 4 units are in the same situation, you have an easier situation than some. It would be harder if only a minority of units/lots had the damage, the damaged areas were common property and it was reasonably debatable whether or not the damage was minor and cosmetic and could be reasonably left unrepaired. In that situation you might have a majority decide to not spend the money to the detriment of the minority who might then have a case that this was a ‘fraud against the minority’.
However, since all are in the same situation, I would say the owners corporation as a whole could decide whether the problem was serious enough for the owners corporation to make the repair. Three owners might decide it was cosmetic only and was not going to become serious as a consequence of failing to make repairs now. In the ACT the Unit Titles Act says:
“An owners corporation for a units plan may, by special resolution, exempt itself from 1 or more maintenance obligations …[mainly the common property]… if the exemption is not reasonably likely to have a significant adverse effect on—
(a) the appearance of the common property; or
(b) the safety of occupiers of the units or of the public.”
Assuming you have some similar provision where you are, the test is whether deciding not to make this repair would be a ‘significant adverse effect’. IE it is permissible to have a minor cosmetic adverse effect but you would want to explicitly resolve that that is what it is.
If failing to make a repair now would mean the ceiling might fall in later or a subsequent repair might be considerably more expense then I don’t think you could decide to leave it.
If it really is only a cosmetic matter and it bothers some owners and not others, you could resolve to hand this maintenance matter over to the individual units owners to deal with (in the ACT anyway). In doing so you would want to make it clear that owners are only permitted to do the minor work and that any matter that could effect the structure or safety had to come back to the owners corp.