For example, that supreme executor D-mod. If the focus was on making the ship more survivable, especially for the crew, we should see that actually happen. The execution has *increased* crew casualties, which isn't just a misguided idea, its a box of short-circuiting gamma cores for an engineering team.
What's actually going on in the fluff is that anyone in a passageway that takes a direct hit from an anti ship scale weapon is going to cease to exist with or without a liner. The liner will do its job and stop knock on effects, ricochets and the like. Even if conduits burst and spill into that passage the only people that are going to be in there are damage control crews that are equipped for it. So in most situations the liners just slow down bulky damage control teams and make medvac teams more awkward around corners. Even if the liners are saving some people they are a hindrance for more.
Andrada was brilliant in statecraft, tactics, and logistics so it's not a leap in his mind that he'd have complete understanding of the nuances of damage control and he's not exactly in a state to be asking for help at this point.
Another thing to keep in mind is that in game the Lion's Guard doesn't actually do much of the Diktat's fighting. Which kind of implies the people tasked with the actual operation of Askonia's defenses have found a perfect solution where Andrada gets to play with his toys but his elite overhauls don't need to actually be standard.