TeamDesk stores and manipulates the data in Unicode, so you can enter text in any language you like.
User interface part consists mostly of customizable table/column/view names. You may translate almost every object on the screen to any language. Few strings that are not translatable: page footer, system menu at the top right corner of the page, search related information in the left side bar and few system messages.
Setup interface is accessible to the application administration staff. They are typically IT related people who usually understand English well.