Wormholes aren't true FTL travel, they change the geometry of space such that there's a new shortest path for light to travel from A to B. Setting up a wormhole between two points requires slower than light travel to extend the wormhole ends. But after initial setup it would still be amazing :-)

If you're interested in some simplified-but-still-roughly-rigorous discussion about the physics of time travel/causality, Sean Carroll did a solo episode of his podcast where he talked about a few different ideas in this space.

https://www.preposterousuniverse.com/podcast/2020/11/23/124-...