Hello @Terence,
in case you haven't figured it out yourself yet.
Here's the solution:
The CSV looks like this:
OBJTitle;Delivery Date;guarantee_period_dialog;guarantee_period_timeperiod
backup0;2019-02-16;by delivery date;3 Years
Now you have to map it like :
csv-accounting.png
And then start Importing. Done
Best regards
Micha