I made a test in Version 3.6.5.2 (Build ID: 5b93205) on XPprof/SP3 using the default Calc sheet.
When I enter 13-02-28 I get 2013-02-28 the default format is yyyy-mm-dd
When I enter 28-02-13 I get 2028-02-13 which is correct when looking at the format
Thus Calc understands “-” correct.
As I have Japanese installed as well, the date format yyyy-mm-dd could come from the Japanese setting. I am not sure what the default setting in other languages is
When I replace the “-” by “/” in the same sheet the situation is
Entering 13/02/28 results in 2月 28日 which is again correct but the year is skipped. Again here come the language setting into the game because the character after 02 is Japanese for month and after 28 is the Japanese character for day.
(If you only see wingdings after the figures there are Japanese fonts missing on AskLibO or your PC.)