Lea Estelle Thierry managed in 2016 a scientific architectural survey and wrote a report about damage assessment. Also, provided a suggestion for a possible protective roofing – Images of that can be found below, at the end of this page.
The reports are available (in German) as PDFs.
Text: Architectural Survey
Text: Damage Assessment
Damage Assessment Mapping
Proposal for a protective roofing. Click image for large version.