No keeper liability means that the registered keeper can not be held liable for the actions of the driver.
There is no requirement for the keeper and the driver to be different people, nor is there any requirement to notify anyone of this if it were to be the case.
The point is that the identity of the driver is not known, the parking company has contacted the registered keeper, who may or may not be the same person. In England & Wales, provided certain requirements are complied with, the driver’s liability can be transferred to the registered keeper, but not in Scotland as you note.
You can contact them if you want, but keep it simple if you do, something like
I appeal as registered keeper.
Liability for the parking charge rests with the driver of the vehicle. I have no requirement to name the driver, and I will not be doing so. For the avoidance of doubt, I was not the driver.
You will be aware that under Scots law there is no mechanism via which liability for the charge can be transferred from the driver to the keeper.
I look forward to your confirmation that this charge has been cancelled
Or you can simply ignore, because nothing will come of it.