I would like to know which was the spoken and literary language in German cloisters during the High Middle Ages. Is it possible to differentiate between social groups in the cloister (monks, laymen, etc.)? I would also be thankful for any further information.
Latin was the lingua franca of the Church, provided a means of communication between people of different areas. It was also the prescribed language of the liturgy. However not all would have known it (especially laypersons and new trainees) so local languages would also be spoken (and quite possibly commonly spoken in non-official capacity).
I seriously doubt much has been preserved to indicate what languages were used in everyday communication between people in convents and monasteries, all official documents would have been either in Latin (if meant for use within the church) or possibly in the local dialect/language of the region if meant for local officials who were literate but not versed in Latin.
It would have been too early for French to have become the fashion language of high society (and most monks and nuns were commoners anyway so wouldn't know it upon entering).