You bring up a good point that the senior pref balance didn't increase. In the past it was a way of accounting for draws: assets would increase by the amount of the draw and senior pref (equity) would increase by the same amount, keeping the balance sheet balanced. But I guess the letter agreement's increase in liquidation preference was not accompanied by a cash transfer from Treasury to FnF so it's not reflected on the balance sheet.
If the senior pref line was going to increase as a result of the letter agreement it should have shown up in the 10-K.
The accumulated deficit goes more negative every time a NWS dividend is paid: assets (cash) go down and accumulated deficit goes more negative to balance it out.
We might be at a point where the total senior pref balance does not equal Treasury's total liquidation preference.