A small patch is on the way to fix a crash when using special European characters on the sandbox setup menu. I understand how much of a pain in the back-side this is for some people, but the most you can do for now is avoid using any non-English characters/symbols in your sandbox level names. This also applies for most other non-American/European alphabets.
Most of these problems will be addressed in 1.3 with the new UI and localization system I’ve been working on, which will allow the UI to do some pretty cool new things and improve the rendering speed of it. It’ll also allow the game to automatically load a compatible font for your region to ensure you can use all your fuzzy alphabets just the way you like them. 🙂
UPDATE: 1.2.1 has been submitted to Microsoft. You should be able to grab it sometime next week.