Athento SE and Athento ECM keep all original documents. All operations over scanned documents add information to the database of the Document Archive solution. If any operation fails, it will be performed once and again without affecting the original document.
Nuxeo indexes the document in a background process every time a new document is created in the system.
When a document is created, updated or deleted, those changes are first stored on the data base. After that, the data is sent to the ElasticSearch node, which is completely dedicated to this work. If indexing in ElasticSearch fails, that does not affect the original document and indexation may be relaunch again.