Thanks. I hadn't been around so I actually hadn't seen the video and neither had I noticed your comment until comments were closed unfortunately. Some thoughts on what you wrote after having watched it and looking at the PCA:

I thought the same thing about those star symbols...If your labelling is correct, it makes me wonder if the label simply denotes "population that provides the (further) western admixture into Yamnaya Romania" rather than "steppe-admixed population that predates Yamnaya in the region" and whether that additional eastern ancestry in that PreYamnaya population is even steppe-related at all or is just excess intermediate HG-related, like in Malak Preslavets, in which case you'd be basically right. I'm even more curious what they might think the Glavanesti samples represent now, especially if the early dating for the more eastern one (or all three, though the Harney et al. ones have very wide dating) is correct.

On the topic of stars: Ukraine EBA (I5884) is almost certainly the one next to Dnieper-Donets, Usatovo Moldova has one on the Khvalynsk-Progress cline and the other hidden behind a Yamnaya dot, judging by the other PCA. Due to help from same, Usatovo Ukraine is the one among the intermediate Balkan Yamnaya set and that leaves the one close to the Yamnaya Bulgarian outlier (Bul4). I suppose this one might be "Yamnaya Paulesti Romania" if the big group is "PreYamnaya Romania" or vice versa, otherwise.

With regard to the mixed Yamnaya Balkan individuals, the more EEF-rich ones don't seem to plot that differently from later CW as you said but they also tend to overlap with the more southern/less HG-rich ones there generally. The upside-down triangle slightly north of that Yamnaya group also looks like it might be the third Glavanesti individual based on color (if that's that case, where's PreYamnaya Bulgaria?). If that's correct, I'm curious if in Vahaduo/Global25 they'll plot somewhere between Corded Ware and ROU_BA. I don't want to read too much into this either way though your thinking is reasonable either way, based on some of the other EEF-rich Balkan samples included here and other HG-rich populations from the more northern parts there we've seen previously.

Those two samples do seem Bulgarian CA but if the more southwestern one is the Mathieson et al. R1b I2181, is the other new or the problematic initially Varna-associated ANI163?

In Vahaduo, early CW seems preferred pretty consistently over Yamnaya for later CW so I wonder if the HG-enriched Don population that overlaps it works as well, even if it isn't the direct ancestor. I didn't notice Anthony stating anything exceptional about the Don Yamnaya Y-DNA though, so I assume it's also Z2103. I also wonder whether its position means that it has extra intermediate HG ancestry (mainline Yamnaya + Ukraine_N) or comes from a more EHG-shifted part of the eastern steppe cline altogether (different EHG/CHG ratio + same EEF). Curious what might be going on with the early vs later Sredni Stog samples that have a similar situation going on.

With regard to theories about Khvalynsk specifically, I think that if early CW, Beaker and Yamnaya are somehow mixes of the same/similar HG-rich EEF and different EHG-CHG populations on the varied Khvalynsk cline (or if CW and Beaker purely so while early Yamnaya is a Khvalynsk-Repin mix, so more southwestern/CHG+EEF? on average at first), then it might add a point for Khvalynsk being PIE-related, though I can think of various issues with that kind of scenario too. If their initial ancestry is similar and closer to the Progress/CHG-rich end of the cline and early CW/Beaker pick up more mixed EHG-WHG in the Ukraine and thereabouts instead, might be harder to argue for it. Khvalynsk is the only sampled so far that shows together all the potential ancestors to the R1 and Q (some in mainstream Afanasievans) that we see in later steppe-admixed cultures, at least so far, with the Sredni Stog samples being female according to Anthony. Shame there's no new R1a and the new Q is apparently a cousin of the one we already have though. And there's of course a big question about what's going on with the very varied Khvalynsk cline in the first place. Is new CHG-rich ancestry coming in right around that time and if so, what does it represent compared to the local more EHG-rich ancestry?