I do not have a specific answer, but here's how I would investigate if I were commissioned to do so:
1) Trace the launching of the import screen.
2) Find in the trace the relevant rules that set those values (granularity and age-handling). Best is if you find a data transform that sets the values.
3) See if there's a non-final relevant rule that you can modify to do what you want. Note that you'll probably want to conditionalize it to only do the modifications if the particular app is being imported for which you want the values to be changed.