-A lot of the things I mentioned in the list aren't necessarily at 'ship tactical' scale. They might be interpersonal skills (especially with the backstabbing thing).

-The Daemon ship might not be something that the current admiral earned. It might be something that his predecessor earned... eh, eh?

-Eldar ships are known to be fast and turn on a dime when you don't expect them to, and have good stealth... so maybe some Imperial that got Eldar tech or something? There are plenty of ways to fool sensors so that a ship appears to be 'not there'; the Chaos Admiral won't immediately jump to the conclusion of 'it's going really fast'. He'll jump to the conclusion of 'it's cloaked or interfering with our sensors somehow'.

-Agree that they may try to cover one another's rear arcs via non-turtling tactics... but it depends on the particulars of the commander, though...

-With so few ships and so few escorts... there are limited areas that are safe from overlapping fields of fire. That is kinda the JOB of Escorts, you know... the escorts that this fleet doesn't have!

-And this is an area with unsettled warp, not necessarily a full, visible-in-realspace, 'warp storm'. It could just be a place that's impassible in the warp but not leaking over.