A320's aren't supposed to be losing fuel while the engines are starting. If there is fuel coming from the drains during start, it's possibly from the VBV's or VSV's, both of which are fuel driven. This is a problem that should get fixed quickly.
On the other hand, if you're seeing a mist rather than liquid, maybe you're seeing the starter air exhaust.
The primary function of the design engineer is to make things difficult for the manufacturer and impossible for the AME.