That's very easy to declare, because automations represent parameter values and since there is no way to translate dB to panning values for instance there is a risc your plugin might crash because it has to cope with a value in a range it might not support the value.
And that is the reason why you cannot copy automation from parameter X to parameter Y.
Really? I thought Automation was always a value between 0 - 1 internally. Sure it displays real value for native DSPs but I thought it probably converted on the fly. For all third party plugs it's got to be the 0 - 1 range though hasn't it?