AppleScript is unable to get a date as string
This may not be a direct solution or quite the answer you are looking for, but this following AppleScript code provide examples of how to convert a given short date string into an actual date, how to extract the elements of the date, edit and set date and time values, and to create your own custom date and time as a string.  Hope this helps.

set dateAsText to "9/23/16"

-- converts dateAsText into an actual date
set someDate to date dateAsText -- date "Friday, September 23, 2016 at 12:00 AM"

-- extract the short date from someDate... as a string
set shortDate to short date string of someDate -- "09/23/16"

-- change the time value of someDate from "12:00 AM" to "5:00 PM"
set adjustedDate to date "5:00 PM" of someDate -- date "Friday, September 23, 2016 at 5:00 PM"


-- extract elements from adjustedDate... as strings
set theTime to time string of adjustedDate -- "5:00 PM"

set theWeekday to weekday of adjustedDate -- Friday
set theWeekday to (weekday of adjustedDate) as string -- "Friday"

set theDay to day of adjustedDate -- 23
set theDay to (day of adjustedDate) as string -- "23"

set theMonth to month of adjustedDate -- September
set theMonth to (month of adjustedDate) as string -- "September"

-- edit values of adjustedDate
set day of adjustedDate to 14 -- date "Wednesday, September 14, 2016 at 5:00 PM"
set year of adjustedDate to 1978 -- date "Thursday, September 14, 1978 at 5:00 PM"

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set customDate to short date string of adjustedDate &amp; space &amp; theTime -- "09/14/78 5:00 PM"