If you just want to display text in a non-latin alphabet you can simply make custom fonts using Decker's font editor, but the underlying text will still be DeckRoman from the perspective of copying and pasting to the system clipboard, typing on a keyboard, or saving a .deck file to disk.
In a sense that Decker will still recognise the base letters within that file while demonstrating/showing it as another appearance-wise? Did I understood it correctly?