I have another thing that should be blocking to update FEP-a4ed. We currently have some python scripts that handle some of the manual work for the FEP process. If one makes change to the FEP document format, these scripts need to be maintained. So changes that increase the maintenance burden should be discussed and someone needs to volunteer to do the work.
I’m writing this due to calls for YAML frontmatter. I must say that this is probably a bad idea. YAML is hard to work with when modifying it using a script. As evidence: The first FAQ entry in the PyYAML documentation is how to get YAML outputted in a specific format. One will face similar issues, if one starts automatically update frontmatters for FEPs. My recommendation: Don’t. Stick with key value pairs.