TheRainmaker
Indeed, the imprint works both ways, as reality is imprinted into this bizarre dimension-space, so is the dimension-space imprinted into reality. However, the modulating fieds are, as expected, absolutely gigantic, thus, the gravitational influence of the ships spread out over a very wide area. Very potent gravitational sensors would be needed to notice this inconceiveably minute change over a gigantic ammount of space, however, it'd be a detectable phenomena.
(Up to you if you detect your lads)
Altraxia
Being sucked up by the newly generated rift, the Dragon faces a much more different fate than the one of the perfectly prismatic Magnaspawn. As it enters the portal, his fabric stretches thin likewise, but translates itself into reality in a stupendous show. His mass slingshot from the Drift at tremendous force, he himself is made into a thin dust that stretches across several systems like a nebula.
The dust however is not normal, as it snaps back into place like a rubber, its elasticity forms back the Dragon, however, it also propells it backwards at tremendous speeds and away from the system it was in, leaving alone the perfect prysm Magnaspawn, which made its travel back to realspace unnaffected.