I have tried to import a simple 1 row .csv file with a date in it (in mm/dd/yyy hh:mi:ss pm format) that I had previously exported from Toad.
I have attempted many times to change the custom date format to no avail. I have even tried removing the time and leaving just the date in the file (in mm/dd/yyyy format) and no matter what custom date format you choose Toad will ALWAYS produce errors for the dates, even when the preview looks good.
I have come to the obvious conclusion that Toad is completely unable to import dates no matter what and wound up just having to type the values into the schema browser data grid 