The symbol on the barnacles is very distinct. It is difficult for me not to think of nebulae when seeing it. If two alien species were trying to orient and find eachother, they might very well use nebulae to direct one another, considering their macroscopic scale. So perhaps they are trying to make contact, giving a location from which the very distinctive Barnard's Loop can be seen in the stamped configuration. Let's assume this for now.
I have looked at Barnard's Loop in the Galmap from all around, and the only reasonable perspective I could find was combining the Loop, Witch Head, and Corona Austr., with the position close to the last of these. The Corona is somewhat oblong, which fits well with the picture. The rough porportions of the two smaller nebula give a range of distances from which they will view correctly. A picture of a view from COL 359 SECTOR EK-D B27-5:
Galmap same location:
The dark region is difficult to see, but they would likely use gravity as much as light to say what is there, as we do. The proportions btwn Loop and the other two are not good either, meaning it probably is in a different system.
There are many systems that have a similar or better quality match to the symbol. I would have liked to find a system a bit closer to the Corona, since the symbol has the loop relatively smaller and also has the oblong shape a bit larger than the circular one, but all systems I deemed reasonable from Galmap had no high metal content landable small bodies and no landable planets at all after visiting.
Here are three systems I thought most promising so far.
Here starts a little speculation. Say the species is attempting to find other life. Say it cannot leave its own system through hyperspace for some reason, but has access to small ftl drives. Their idea could be "find advanced life", much like SETI. So send out probes (UAs). For some reason (new ftl tech unstable? sending a signal home by perverting our machines?) their technology messes with our own. But they do get a signal back home. So then they send out maps and gifts to us, having found other life, hoping for a nice first contact. Or something devious, I guess?
Anyway, it all revolves around the nebulae because, again, they are what everyone can see. They are relatively small regions of space that advanced life will visit, if only for curiosity. So they sent probes to nebulae. They got hits in the Pleiades. It's right by the very distinctive Barnard's Loop, so they send a picture of what the loop and surrounding nebulae look like from their perspective, hoping we'll visit.
Well, I'm around that area. I'll be checking it out in the next few days, if things don't blow past me.