What I would try to do for simplicity is to avoid using the excel exporter module.
I would use the datagrid 2 export (via javascript)
There's a clip over how to do it here
HOW TO EXPORT AN EXCEL ON DATAGRID 2 | MENDIX 10
The advantage is that you will be exporting only what's visible in the grid. So this means you can change the sorting of the datagrid and the export result will match that.