Wassebourg was brought up within the entourage of the dukes of Lorraine. He received his education at the University of Paris, and for 30 years held positions there, at the College de la Marche. He had access to the best libraries and archives, as he was by profession a historian and a scholar. He was also Archedeacon of Verdun.
https://en.wikipedia.org/wiki/University_of_Paris
https://en.wikipedia.org/wiki/Coll%C3%A8ge_de_la_Marche
Here is a nice photo of a statue of Charlemagne standing on top of "Verdun".
https://en.wikipedia.org/wiki/Verdun#/media/File:Verdun_4juni2006_0...
Thank you Ulf. I cited it at the beginning of the discussion and included a bit more of the text. It should still be there for anyone interested in reading it.
And as Juan patiently brought to our attention, Barengar and Willa were connected to the house of Burgundy. Barengar and Urraca were quite familiar to them, as they were the namesakes of Spanish and/or Iberian royals.
"Reginaldo I of Burgundy. Reginaldo I count Palatino de Burgundy, (986-1057). He was the second count of Burgundy. He was the son of Otto-William of Burgundy, first count of Burgundy, and Adelaida Ermentrude de Reims and Roucy. His maternal grandparents were Reginaldo de Reims and Roucy and Alberada de Hainaut, while his paternal grandparents were **Adalberto II de Ivrea** and Berberga de Mâcon.
"Raymond of Burgundy (Besançon, 1070 - Grajal de Campos, September 20, 1107) was a French nobleman who introduced the Burgundy dynasty into the kingdoms of Leon and Castile having married the eldest daughter of King Alfonso VI, the Infanta and then **Queen Urraca de León** (her g-granddaughter was Berenguela I).
"...The House of Burgundy was a dynasty whose owners reigned in the kingdoms of Castile and Leon, from 1126 to 1369. It was a collateral branch of the **House of Ivrea** that ruled in the county of Burgundy.
http://biblioteca-fag.blogspot.com/2018/03/casa-de-borgona-de-casti...
"...the House of Ivrea were a medieval Frankish dynasty of Burgundian origin which rose to prominence in Italy in the tenth century, even briefly holding the Italian throne.
https://en.wikipedia.org/wiki/Anscarids
Richard de Wassebourg was a very well-educated scholar from a powerful family closely connected to the family of Gothelo I (the dukes of Lorraine), a high-ranking cleric in the church, and a respected historian.
It doesn't matter when he lived, because he had access to the relevant records and texts. He had access to Hugo de Flavigny's chronicles, too, which were written during the time of Berengar and Gothelo. The Jesuits purchased an original copy of Flavigny's work and held it in their library for safe-keeping.
https://books.google.com/books?id=CdUIO_fYRxQC&pg=PA5&lpg=P...
https://books.google.com/books?id=OC1KDwAAQBAJ&pg=PA33&lpg=...
https://books.google.com/books?id=A2_eCwAAQBAJ&pg=PT78&lpg=...
(Check out the footnotes, too.)