Changing what code?
There is nothing in ACF that will help you with this.
You should look at what WPAI can do or cannot do. That plugin, besides providing import for repeater fields also has its own filters that allow you to modify how importing is done if you need to. For example it can be used to modify the content of a cell before it is used. You can also run custom functions on cell contents during the import. The support over a WPAI has always been helpful to me when I need to do something special and I would suggest contacting them.
I do not have sufficient knowledge about WPAI to help you modify your import to work with the data you have.
