Hello!
First, thanks for using the Asset!
So, I did some investigation on this issue. I tried publishing your module and testing the API by my self, and after a few attempts, I was able to make it work! Just be aware that i changed your currentdate - ETA condition to > 2 days.

The fix I performed was to change the Java Script code on "GridOnInitialyze" with this one:
id = $parameters.GridWidgetId
OutSystems.GridAPI.GridManager.GetGridById(id).provider.updatingView.addHandler(function(grid) {
grid.rows.forEach(function(x) {
if (x.dataItem !== undefined &&
x.dataItem.ETA !== undefined &&
(new Date(x.dataItem.CurrentDate)) !== undefined &&
(new Date(x.dataItem.CurrentDate)).getTime() - (new Date(x.dataItem.ETA)).getTime() > 2) {
OutSystems.GridAPI.GridManager.GetGridById(id).features.cellStyle.addClass($parameters.Binding, x.index, 'background-red', false);
}
});
});
OutSystems.GridAPI.GridManager.GetGridById(id).provider.refresh();
Regards!