Any text entered into the SD card option is automatically capitalized, which can be a pain. For example, a multi-config with a user-defined axis of sd =

can be entered into the SD card option box as ${sd}. However, all builds fail, and looking at the project configuration shows that the text was changed to ${SD}. The offending code is in EmulatorConfig.java:
sdCardSize = sdCardSize.toUpperCase().replaceAll("[ B]", "");

A similar issue probably exists with locale due to this:
deviceLocale = deviceLocale.substring(0, 2).toLowerCase() +"_"
               + deviceLocale.substring(3).toUpperCase();