Hey Matthew and Welcome to ET! From what I can gather, there were no planned interior design changes to Britannic's 2nd Class Public Rooms. With the Aquitania's grand 2nd Class Public Rooms, I would like to think Britannic's Public Rooms in second class would have been improved.
Perhaps someone else can shed more information on the subject, as I am only familiar with the changes made to first class.
Thanks for the imput and that is a great site, it's been marked as one of my favorites for quite a while.
I assume that White Star would have modified the second class areas Britannic as they were investing the time to do so to the first class areas of the ship. It would very interesting if any such plans came into light- I would love to see what might have been.