As I understand it, thanks to the General Relativity it is absolutely impossible to have both relativity and FTL without the latter opening you a way to get into your past thanks to the relativistic frame shifts, thus destroying the causality, which in turn destroys the entirety of physics and science, undoing everything we've achieved in an instant.
But can the time-travel aspect be obfuscated enough to shift it into "hypothetically possible according to the abstract math, practically impossible according to the complexity of the reality" area, making its reality-unraveling capabilities be unreachable at least for the normal characters in the setting?
The FTL system in question works via the existence of an expensive device that creates a wormhole of a greatly reduced (But never zero) length between two points in space, presumably by taking a shortcut through either another universe or through some high-dimensional witchery (It's a replicable black box device that nobody exactly understands). The spaceship then needs to travel through the wormhole under its own thrust, carrying the device with it along the journey. The wormhole supports normal spacetime only in the vicinity of the device, so it can't be used for FTL communications or attacks (You can't strap the device to a radio wave or laser beam).
Current limitations imposed by the setting is that the system cannot establish a wormhole to and from an area with a significant gravity gradient (preventing jumping to and from near planets and other heavy objects, forcing you to go away from them before initiating the jump), and it cannot establish a wormhole between two points that exceed a certain relative velocity from one another, which hopefully should prevent the "jump to the object moving at 0.999c, jump from it to your own past" situations. Both attempts result in the wormhole being unstable and collapsing instantaneously.
Would these restrictions be enough to prevent the time travel from being practically achievable?