On Earth, the cardinal directions are straightforward. The arrow on a compass points to the nearest magnetic pole. You can then use it to travel anywhere on Earth.
In space, the idea of anything being “central” enough to be used as a “North” (since the universe has no center) or being fixated enough to not somehow pose issues is more convoluted.
If you were a pioneer of space exploration, what would your “North” be?
I’d use Discworld nomenclature:
Fun fact, widdershins is a real word, it used to be used for talking about someone walking around a church counter clockwise, which would make it possible for a demon (or fae?) to snatch children up
What about catywampus?
Also up and down, I assume?
I’d probably just make that height over or under the middle of rotation
A few problems with this. That requires a world experienced in 2D, with one axis being towards or away from the centre, and the other being clockwise or anticlockwise. Works great when discussing intragalactic travel, but OP specified intergalactic travel. Where there is neither an obvious centre point nor a single plane on which things predominantly occur.
Though fwiw, language very similar to that is legitimately used in some real world languages. Some Malayo-Polynesian languages, such as Manam, talk about direction in terms of seaward, inland, clockwise, and anticlockwise.
You can prefix the coordinates with the name of the current nearest star or center of galaxy.
Universal coordinates are fairly useless anyway, given how everything moves around in space.