I don't think they are, but it's easy to put them in the right spot just by looking at pics of other cars on Google Images, they don't have to be mm precise.
I purchased one of these
https://www.ebay.co.uk/itm/391831521782 and it makes a very clean cut exactly where you want it (after making a suitable smaller pilot hole of course). 18.2mm is the common hole size that all genuine VAG/Skoda cars use, not sure about the cobra system or how OEM they are.
This is the system I purchased
https://www.aliexpress.com/item/32866042537.html? Completely OEM (I have an RNS 510) but does require some coding and effort to fit nicely.
If you've got an ED30 it's worth doing right, no?
Good luck
Stu