Odd that it should come up in Gàidhlig but if you go to Roghainnean > Roghainnean you can set the dictionary file (under Faidhle an fhaclair) to irish.dic and if you hit the Roghainnean tab on the far right, you can set the user interface to Irish too.
As far as Safari goes, no idea I’m afraid, it ought to work but it’s not a browser I use much so I’m not sure why it would object. The Mac (assuming Mac because of your Safari question) file is [url=http://sourceforge.net/projects/scrabble/files/Main_Program/MacOS/Scrabble3D-darwin.dmg/download]here[/url], maybe a direct download works better?