I think I figured it out. It works when you escape strings with forbidden characters using quotation marks, like this:
---
aliases: ["@author2007", another alias]
---
So perhaps this could be added to the documentation at Add aliases to note - Obsidian Help?
In any case, the bug turned out to be none, so I’m moving this topic to #get-help
While experimenting, I also noticed that having more than one aliases: line in the header will break all of them (i.e. none is recognized as a valid alias). It would be great to have a setting to change this behaviour to “use last” or “use first” instance of the tag.