Please be aware that the current OPC-UA implementation supports only objects with an idempotent character.
Elements like cmd do NOT lead to idempotent reaction and are therefore not supported so far.
UAExpert lists the non supported types like shown in the above figure or noted here:
Which objects are affected? A small range of motion-axis commands is shown exrmplarily right side.
In generell all the object which are operated by the POST-method in case of runnig REST-API communication.
On the other hand the objects operated with REST methods PUT/GET etc. lead to idempotent reactions and are supported yet. Several times invoking the same REST - GET/PUT will lead to the same result. The REST-POST differs.
Further details regarding timeline can not be published so far.