It's strange that we know every detail of Kaylee and Maddie's night and not much about Ethan and Xana.
I've felt the same. As with many other aspects of this case, the information LE chooses to share with the public seems telling of their investigative strategy but could just as well have a simpler explanation.
The Sigma Chi house, where E and X were confirmed present earlier in the night, is within walking distance of the King Street residence. It is almost literally "across the street". Know this, and knowing that K and M had been at the Corner Bar before arriving home, perhaps they felt early on that the public would be a much greater assistance to finding a suspect who targeted one or both of K and M that night specifically. They were in public areas with people of different ages and backgrounds and had to traverse a good portion of the town to get home. Maybe they felt like conducting interviews with other party-goers at Sigma Chi that evening would be immediately more effective than overtly encouraging public think about what they might have seen in a small area they likely weren't in on that night.
At the same time, sources close to the case have said that not all neighbors were interviewed. It seems like that would be useful in establishing whether E and X had been followed within that small area between the residence and Sigma Chi house. It also doesn't explain the large time gaps in E and Xs location per the map shared by LE diagramming each of the victims' movements that night. The caption on E and X's initial location reads, "2000-2100 Ethan and Xana attend Sigma Chi Party. 735 New Perce Dr." Maybe this has already been cleared up (sorry if it has), but how is one meant to interpret that? Is that the timeframe in which they arrived at the party, or is this the approximate total time of their attendance (1 hour between 8 and 9 PM)?
In the case of the latter interpretation, this leaves an almost 5 hour time window to E and X's return home. At this point, LE have phone records which, fairly precisely, map the movements of each victim that night. Maybe LE is keeping E and X's movements confidential as to not compromise interviews with people connected to them. Maybe an indication that someone knew where they were outside of Sigma Chi that night would make them a person of interest. Maybe they feel E, X, or both were the initial target.
It seems more plausible to me, that LE is strongly convinced that either K or M was the target. But there have been so many public-facing aspects of this case that just add to the confusion. I understand the value in keeping certain clarifying information confidential, but I also believe that LE has at times been very poor in communicating the information they do want to reach the public.