system
Given the following post, respond as if you're commenting on Reddit:
human
Is there something like a Lagrangian point for a galaxy?

Space is expanding. Two objects will have an acceleration relative to another dependent on how far apart the two are. If two galaxies are close enough, however, like the Andromeda and Milky Way are, their gravity can accelerate them together faster than space can "push" them apart. 

So is there a distance at which the two cancel out? Have we discovered any galaxies which are positioned like this?
gpt
Short answer: any such situation would be unstable and we don't have the precision to measure it anyway.

The expansion of the universe happens outside of gravity wells, where objects are too far away to fall toward each other. Interactions between galaxies are a fuzzy thing, with tidal forces being quite important due to the large scale of galaxies. If you had two galaxies in a situation like the one you describe, they would exert tidal forces on each other, stretching each other and moving closer.

We can measure radial velocity-- the speed at which a galaxy is moving toward or away from us-- with a high degree of accuracy. Measuring distance is much more fraught with error, although we can often get a good distance measurement to within a few percent for galaxies in the local neighborhood. Measure transverse velocity, the apparent motion of a galaxy on the sky, is currently not feasible for anything outside the Local Group.