When I first opened tweetdeck I had the same reaction as most WOW. Well it's beta and there are lots of bugs, one of them is its international font unfriendly when first installed. Let me explain, when first opened woo nice hey?
Look closer and you can see the text from Satoruy is missing!! Actually all non roman fonts wont show, the workaround is:
click on settings (the little spanner on the top right)
A popup will appear
Then click on the Colors/Fonts tab.
Now check "International fonts" and close the popup.
Haven't tried it on mac but I am sure any Unicode base OS wont have the same prob.