Excuse my old terminology Blackmail, but the issue is to gain knowledge of what was displayed on the “EFIS / ADIs / artificial horizon”. With the particular equipment fit it appears most unlikely that anyone will know what the crew saw, even with your exotic description of an inertial platform. Another argument for a video in the flight deck.
What follows is just uninformed guesswork.
I noticed that three columns in the tables beginning at page 227 of the .pdf file are labeled PITCH ANGLE EFIS / ROLL ANGLE EFIS / MAGNETIC HEADING EFIS. Does this mean that the DFDR actually records the data available to the crew through the EFIS?