I think it’s too late for the Inform 6 compiler and its libraries, but it would be interesting, for translation, to be able to customize in the source code of the game, the messages sent, during the game, by the interpreter.
Some examples of messages with Frotz unix:
[More] [Hit any key to exit.] Enter a file name. Default is "": Cannot open file Overwrite existing file? Do you want MORE prompts? (y/n) >
If the interpreter could take these messages from the source code of the game, it would be nice!