You could leave out the "is" but not the "the", but it would sound accusative. "She the treasurer and he the Secretary."
This is because essentially in English we treat a job title like a title, perhaps going as far as referring to people by their title, "madam treasurer, Mr Secretary."
Misleading and completely wrong. Omitting "is" (the verb) means this is not even a sentence! An article is optional depending upon context - there must be thousands of amateur sports and hobby clubs where a keen individual is introduced to new members as "Mr A, Secretary and Treasurer of the XXX Club"
This will confuse you, but they are actually different jobs.. run this through google translate https://onzetaal.nl/taaladvies/advies/secretaris-secretaresse