Bad design
Who said newer means better? That saying is usually correct but not in this case when this young couple bought an apartment in a new building, only to experience leaks the next day. The realtor must have been one shady character and managed to stop the leak just long enough to make the sale.
It seems like you just can not trust anyone these days and now this young couple will have to pay extra money to get this all repaired. How much will it cost now to open up large parts of the ceiling and find out what exactly is leaking and where?