editortranslator behavior is elegant, but leads to some problems. For example, in APA style, an edited book with a translator should be cited as:
Editor, A. A. (Ed.). (Year). Title of book. (A. A. Translator, trans.). Place: Publisher.
If the editor and translator are the same person:
Editor, A. A. (Ed. & Trans.). (Year). Title of book. Place: Publisher.
Handling both of these cases isn’t possible. If
variable="editor translator" is used, the first reference will yield:
Editor, A. A. (Ed.), & Translator, A. A. (Trans.). (Year). Title of book. Place: Publisher.
This is unfortunate, but not sure if it is common enough to bother addressing. If the issue is to be addressed, I think the simplest solution would to adopt
editortranslator as an explicitly callable variable (with the variable still being automatically generated as currently). Then, the current style coding
variable="editor translator" could be replaced with
variable="editor editortranslator" meaning “editor, including the
editortranslator label if necessary”.