I did raise a ticket about this a couple of weeks ago. Basically the warnings show around 800 pages on my site where the Twitter card is incomplete.
Twitters own support site for this states that it will fall back to using open graph title and description if the Twitter card is not present. Therefore if the og versions are available I dont think this should show as a warning.
I appreciate what you said in your response whereby warnings are “best” recommendations. However, within those 800 warnings I may have some genuine pages where the information is missing.
Without going through each page and updating, which is not really necessary as Twitter can get the necessary info from og tags, I would be unaware that there are pages where this information is actually missing.