Apart from Asens,another important clue that the Cumans were quickly assimilated by the Vlachs is Belaur's name,definitely coming from the Romanian- inherited Balaur,a common name even today,related to Albanian Bolla,Bullar.
https://en.m.wikipedia.org/wiki/Belaur
https://en.m.wikipedia.org/wiki/Balaur
https://en.m.wikipedia.org/wiki/Bolla
https://en.m.wikipedia.org/wiki/Belaur
https://en.m.wikipedia.org/wiki/Balaur
https://en.m.wikipedia.org/wiki/Bolla