In fact, the duplication of rotation was not supported and we added that recently (like example I sent above); which is the right implementation for the rotation on many qubits. Note it means a separable operator where rotations act on different qubits (like tensor product you created above).
What you are talking about is the Ising coupling between different qubits (which does not mean as rotations on many qubits), and it is supported in our framework. For example for R_zz(theta) we have
QuantumOperator[{"ZZ", \[Theta]}]
Note R_zz gate is defined for only 2-qubits. So a bad code like this:
QuantumOperator[{"ZZ", \[Theta]}, {2, 4, 6}]
will be interpreted as the Ising coupling between qubit #2 and #4 only
QuantumOperator[{"ZZ", \[Theta]}, {2, 4}]
I hope it helps to clarify your question.
