I reckon, that this means "books acquired by the Stauffian Emperor". The court of the Emperor is not really an institution to make gifts to: it is ephemeral and volatile in its composition, unless you wish to use the administrative body of the Sicilian kingdom as a court (which requires that the library is in Sicily and likely in Palermo). And you can not really distinguish between gifts to the Emperor and his other acquisitions.
Should we continue modifying the Charter of the Covenant of Triamore (Triamore p.34f box) now?