CatBatty and Bev are my heroes. You have pulled this together in record time and it is amazing.
Could you add this to the list of things to look at:
In the Last Post By column, the avatar is displayed. Could you explore using the Display Name instead of the Avatar. Display Names are more recognizable than Avatars. Plus, I use the setting that turns off Avatars to save loading time and display space, so in that case the last post by column is blank.