there is something out there that said the Thargoids entered from the other direction last time, it was a observations thing that got shut down just after making the discovery that they have been here all along and never went away. I will see if I can find it on the forum.
The megaship that was discovered corewards of the bubble was supposed to part of the operation watching for Thargoid activity. Either it's present location isn't related to the mission, or at some point people in power were watching corewards. Also, the logs recovered from the various Rift bases talk about seeing things in witch space, unexplained power cuts, unexplained dropouts from witchspace and various things that sound very much like Thargoid activity. Which would imply Thargoid activity in that direction too.
In Premonition, it mentions those things too and links them directly to Thargoids and also directs attention to the Col70 sector, but other than the events right at the end, the other large thing that happens in Col70 is the massive Wreaken construction site of Fed and Imp capital ships. So... it's all a bit ambiguous.
It feels to me like maybe the Thargoids are only using Col70 as a staging post? Certainly there's absolutely no Thargoid sightings around Col70, most activity and interactions seem to be occurring around Merope. It doesn't seem to gel together currently, I suspect we don't yet have all the info.