If you’re saying that the shower recess has a leak for which the Owners Corporation (O/C) is responsible to repair because the tiles etc are those originally fitted when the building was constructed, and they’re fitted to the floor and/or an external wall of the Lot, then YES the Lot Owner could ask that O/C to make a payment to them that’s equivalent to its costs to repair only those Common Property areas of the shower recess.
And YES the Lot Owner could put any payment from the O/C towards their costs to renovate (the bathroom) provided of course that they’d first obtained the O/C’s written consent to the entirety of those renovations.