Being on an AEA principal contract does not indicate whether or not a role is Leading. Not in the general sense of the term, nor in the Tony Awards' definition.
If the OP meant "leading role" according to the definition as per Tony Awards placement, refer to my previous reply. If they meant in the general sense of the term "leading role" then, regarding INTO THE WOODS, or any other show for that matter, it is up to interpretation.
"The Spectacle has, indeed, an emotional attraction of its own, but, of all the parts, it is the least artistic, and connected least with the art of poetry. For the power of Tragedy, we may be sure, is felt even apart from representation and actors. Besides, the production of spectacular effects depends more on the art of the stage machinist than on that of the poet."
--Aristotle