Wikipedia is unfortunately reporting the "traditional" account, but it is, to put it mildly, underdocumented.
Medieval Lands goes into the problem in a bit more detail:
c) ROBERT [Rodbert] . "Rubertus filius Ruberti comitis" donated property "in in pago Wormat. in Mettenheimer marca" to Lorsch by charter dated [836/37][827]. [same person as…? ROBERT "le Fort" ([815/30]-killed in battle Brissarthe 2 Jul 866). No definite proof has so far been identified of the co-identity of Robert "le Fort" with the son of Robert Graf im Wormsgau. No primary source has yet been found which points specifically towards this suggested co-identity, although it is consistent with the Franconian origin referred to by the Annales Xantenses and by Widukind, noted above. It is assumed that the suggestion is based primarily on onomastics, although the first secondary source which proposed the connection has not yet been identified and therefore has not been not checked. The author in question may also have assumed that Robert was a unique name among noblemen in France in the first half of the 9th century, although this ignores Robert Seigneur [comte] à Sesseau en Berry, who was the possible brother of the wife of Pepin I King of Aquitaine (see the document CAROLINGIAN NOBILITY). The timing of the supposed arrival of Robert from Franconia, assuming that the co-identity is correct, is not ideal either. Robert would presumably have fled Germany after opting to support Charles II “le Chauve” King of the West Franks in the latter´s fight against his brother Ludwig II "der Deutsche” King of the East Franks. This dispute is dated to 858/59: King Ludwig invaded in Aug 858, when King Charles was faced with widespread rebellion, and was defeated in Jan 859. However, Robert "le Fort" is already named as missus in Maine, Anjou and Touraine in Nov 853, in a document issued by King Charles II[828] (unless of course this document refers to Robert Seigneur [comte] à Sesseau, which is not impossible).]
