I sympathize with your distaste. Languages and datatype could have been predicates of the named tuple or object, which would have given languages more flexibility in different domains, including more properties on the languages themselves.

On the other hand, the language tag drastically reduces ambiguity and processing cost in a collaborative multi-lingual dictionary. But that’s a datastore implementation detail, not something that should be encoded in the abstract or serialization formats.

JSON Triple Sets flattens the triple (octuple?) with s, p, o, s_type, p_type, o_type, o_datatype, o_lang. This could be implemented with a consistent hierarchy:

{s_value, s_type,
p_value, p_type,
o_value, o_type, o_datatype, o_lang}

or

{ s_value,
s_type,
p : [{ p_value,
p_type,
o : [{ o_value,
o_type,
o_datatype,
o_lang,
}]
}]
}