Romania is a big country. Modern day Wallachia and Moldavia as origin points are very unlikely. But Transylvania is something else.
These Pannonian E samples are from areas near the Romanian border. This used to be Hungary 100-1000 years ago, so one might say "Eastern Hungarian" areas as well for that region..
Psenicevo which is full of V13 together with Babadag cousin culture both descend of Insula Banului (this is probably the most important thing for Balkan V13) group near the Iron Gates, this is where Gava people merged with some Incrusted Pottery locals.
NE Hungary has LBA E-L539 level sample with lots of Steppe, according to diagram 47 % Yamnaya, even EBA E-L539 sample had 39 %, so it seems in Southern expansion V13 mixed with some very Southern group with as this study suggests with some extra CHG ancestry (which is what that old EIA Bulgaria sample shows) giving them a profile that is more Aegean like. I think the explanation for this are some extremely Southern LBA and EBA samples, both J2a also from NE Hungary. Apparently one of dominant Transylvanian cultures Schneckenberg (which I used to connect to V13 long ago) was of Anatolian origin, and its cousin culture from Bulgaria in this study also has J2a.
And also after the spread of Psenicevo and Babadag, another younger IA culture appeared Basarabi, which spread also Westwards, this Croatian sample is most likely result of those Thraco-Cimmerian movements as we saw already V13 in Vekerzug context.
I was surprised too with E-BY14160 in LIA Bulgaria. Parent clade Y37092 is mostly Western Balkans today. There is only one Macedonian E-BY14150 sample.
Scythian LIA sample and that group whole from Moldavia also is from an area and with some material of an IA group clearly descended from the South, and prior to that from the Insula Banului areas.
We do have one female Babadag culture find MJ12 (and that's because I bothered to look at that site, most call it just Thraco-Cimmerian), it also shows plenty of autosomal affinity with what looks to be the dominant IA V13 autosomal profile.