Just a short hint:
if there is an author with Roman Numerals in the author field like
Denniston R. H. II.
it will be changed to
Denniston, R. H. I. I.
with the Extract Citations feature.
Or is there any markup to prevent this?
in the initials part of a person name, there's currently no markup that allows to distinguish between initials and uppercase-only chars that carry another meaning.
However, can't you put the name suffix (such as "II" or "Jr.") after the authors last name, like this:
Denniston II, R.H.
This should allow for correct formatting in citation output.