I agree with theducks, best way to handle anthologies/omnibus editions is to split them up rather than trying to somehow shoehorn the concept of a book that is actually multiple books into calibre.
As for tagging the role a person plays in the book creation process. That is IMO a level of detail too far for core calibre. You can simply add that info in freeform to the comments field, or if you really want to manage it in a column, then create custom columns for the common types, such as editor, illustrator, translator, etc. And simply enter the names in those columns.
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