Wikipedia capitalizes the title of Samuel Beckett's Waiting for Godot as En attendant Godot in its original French version, which is how the title of the play is originally typeset. However, according to MLA formatting (MLA Handbook, Eighth Ed.),
Whenever you use the title of a source in your writing, take the title from an authoritative location in the work, not, for example, from the cover or the top of a page. Copy the title without reproducing any unusual typography, such as special capitalization or lowercasing of all letters.
It then continues by describing which words to capitalize, concurrent with standard title case. I plan on capitalizing the title to be En Attendant Godot by the rules stated above, but I am wondering if there are any different rules for titles in languages other than English. For example, I know that Spanish titles often only capitalize the first word, but I don't know the MLA rules in Spanish, either.
Edit: I have found that the last few pages of the English version Waiting for Godot: A Tragicomedy in Two Acts gives the following:
WAITING FOR GODOT was first presented (as En Attendant Godot) at the Théâtre de Babylone, 38 Boulevard Raspail, Paris, France, during the season of 1952–3.
The only reason I still cannot fully justify that capitalizing or not capitalizing either is correct is because the play itself could have been capitalized differently than the book. I really have no idea.