I recently studied this topic and went through the remakable document from the RR Australian forum
and believe an addendum should be done.
When you replace the original rocker cover cork seal by the rubber ones, some parts need to be replaced by others, as specified in the above document..
But, under the original cap nuts, which remain the original ones, you definitely need to add a washer joint " XB 1079 " per cap nut, at least on my Continetal R and I would say on all models.
This is not specified in the above document and remain indeed essential, otherwise the work is not done accroding to Bentley requirment.
You could check on a technical draw from Bentley what I mean, you will see that 6 Washer Jonts XB 1079 R are necessary when replacing cork seals buy the rubber ones.
With the original cork selas, you are not supposed to have those 6 washer joints XB 1079 R, and in any case, would you have them, they should be replaced as they are in aluminium.
But they do not appear on original Bentley draw with cork seals.
I let you report my comments to the original author.