Nice one! Much to consider.

JEDIT: So having considered it, though it’s nice to have the Imperial fortress before the First Order, it reintroduces that awkward sentence construction that I’ve tried hard to avoid this time.

I worked a bit more on the second paragraph and came up with this:

In Skywalker’s absence,
warriors raised in exile
under the cruelty of the
IMPERIAL FIRST ORDER
have emerged from their
fearsome hidden fortress
to terrorize star systems
throughout the peaceful
New Republic.

This puts the responsibility for malevolence on the First Order rather than the soldiers, and also works in the idea that the Empire was actually exiled after their defeat.