M. Marion, 'Une bibliothèque ecclésiastique: les livres de l'abbé de Rothelin', Revue française d'histoire du livre, 56 (1987), pp. 201-11 states that only 27 items in the catalogue are pre-1500 MSS. Finding them among the more than 5000 lots would be tedious if it were not for an index at the back of the catalogue listing the lot numbers of MSS (including the post-medieval ones). Many are books of hours, but there are also non-religious texts such as the Roman de la Rose, Chronicles, etc.
Among the manuscripts are the Bible historiale illuminated by Jean de Bruges, presented by Jean Vaudetar to King Charles V, now in the Meermanno-Westreenianum Museum in The Hague, and the Sherborne Missal at the British Library:
A blog-post elsewhere provides a biography of the Abbé and usefully reproduces his bookplate:
