First of all, there's heavy regulation when it comes to banking software. There are laws and bank regulations that are here to prevent people from losing their money and/or suing the bank for some reason or another. Root needs to take great care to ensure that the software written by their users stays within the boundaries of south african law and their own bank regulations.
Second, the software absolutely needs to be reviewed not just by people from Root but also by a reputable independent consulting company.
Third, Root mustn't allow direct initiation of transactions from their platform to prevent potential disastrous effects due to bugs. You should be able to write code that does something when the money is being received or sent from your account but not code that charges your account.