I have downloaded Google Chrome and is working fine, seems like it is the script that allows you to write text and how it is generated on Safari. Shouldn't matter whether or not you are using Safari on Mac or Windows as they are the same programme and like you said uses the same engine, the problem is that Safari can interpret some parts of some scripts differently to other browsers and well when the game was made, it is clear it would had been optimised for both Internet Explorer and Google Chrome as they are the web browsers that are used by most people.
So I suggest until they have fixed this, just download Google Chrome and use that (if you are using a mac) or just use Windows Explorer (if you are using Windows).
Like I said the team is aware of the problem and have received quite a few tickets about the problem and are now looking at solutions to fix the problem