CPE, C2 writing

Here are some details about C2 writing. First, CPE https://www.cambridgeenglish.org/images/cambridge-english-assessing-writing-performance-at-level-c2.pdf

In Google

PDF with guidelines and models

EOI http://www.eoi.gva.es/va/avaluacio

In EOI Valencia's web, there are files with examples of the exam, but they do not specify the criteria they use for the writing. You should note on the English Explained page that mistakes in areas considered basic are more heavily penalised, so read and re-read your work carefully!