Actually I started to notice some AI improvement. Outnumbered raiders taking defensive formation. I can see the same behavior with looters.
I am not sure if it's the 143 or the Realistic battle mod.
The video is not the best quality (PC issue) but it is visible the Sea raiders are picking the right location and proper defensive formation. Nice
That has been in-game for months. There are other spots on other maps where they'll do similar things, like one of the steppe maps they'll cluster around a large boulder to shield themselves from cav charges and arrows on the flanks or a plains (I think) map where they will use a very slight decline as a reverse slope position if you have lots of archers.
And there is of course the notorious "go stand in the middle of the river" defense...