The current definition of 'any role' states:

...Any role it indicates that any role value apart from the implicit ARIA semantics role value, MAY be used.

this definition should be updated to indicate that this is not a carte blanche invitation to truly add 'any role' to an element.

For instance, we should make mention of the fact that any specified role must also follow the rules of use as outlined in the ARIA specification. e.g., <i role=gridcell> is valid per <i> allowing 'any role', BUT it would be invalid to add this role to an<i> if that element were not owned by a role=row, which that would then need to be owned by a role=grid.