Returning to Eckhard's Latin translation by Peter:
"Besides, the Testament (will) (of) Everhard, (which) Adalroch his nephew signed, whose regard of Everhard inhabits the same account (the will document). And certainly it is (a) parallel, or perhaps his father Henry (the) Swiss, considering how again in the case of Folcardi Mirac. St. Pertini forced out Count Henry, whereby afterward, Folcuinus (was/became) Bishop of Morino (in the) year 839. (A/The) signed letter testifies how the Bertinian Monks were restored as Custodians of the Basilica of St. Mary."
It seems perhaps that Unruoch was forced out of the Sithui abbacy according to Folcuin III, monk at Saint-Bertin 's (d975) hagiography ‘Miracles of St Bertin’ and eventually replaced by the hagiographer's ancestor, Bishop Folcuinus [Folcuin, Bishop of Morins [Thérouanne] ] (d 855)
Is this in line with what Defries describes here: "Lay abbeys began as a way to protect monasteries from elites who seized monastic wealth and properties"? [Could the elite here be Unruoch? d <853]
After all, by the 1820s Sithiu housed 130 monks and controlled about 100,000 ha of land.
[And ultimately Unruoch’s descendants will be 3 successive generations of Abbots at St Bertin: Firstly his son Adalhard: Adalhard, abbé de Saint-Bertin († April 3, 864 ), then his grandson, Adalhard (acc to wikipedia)Adelhard von Burc, abbé de Cysoing († after July 1, 874) and then his other grandson Raoul / Rudolf Rodolf, Abbot of Cysoing and St. Vaast († May 1, 892 ) https://de.zxc.wiki/wiki/Abtei_Saint-Bertin - both the sons of St Eberhard, margrave & duke of Friuli
So if we to return to the primary sources for UNRUOCH (Unruoch, marquis & duke of Friuli for this period they show:
Comte en Ternois 839. "Unrici comitis" signed a charter dated 20 Jun 839 issued by "Folquinus…Morinorum episcopus"[Saint-Bertin (Guérard) Liber II, IV, p. 85. ]. This is Folcuin, Bishop of Morins [Thérouanne] Charles Martel's grandson and Charlemagne's cousin
"Undrici comitis" signed a charter dated 29 Jun 839 issued by "Hugo abbas…Sithiensis"[Saint-Bertin (Guérard), V, p. 88. ]. This Hugo Abbas Of Sithiensis is Charlemagne's son: Hugo, Archchancellor of the Empire
Monk at St Bertin [Settipani (1993), p. 257 footnote 455. ] I cannot find the Settipani original, but it would be interesting to know if this references Unruoch becoming a secular? monk in St Bertin before he was ousted by Folquinis (as Eckhard tells us) or afterwards in old age, and before/ while his son Adalhard, abbé de Saint-Bertin († April 3, 864 ) is Abbot there?