Collaborating to improve cultural heritage collections as data: analyzing Europeana and Japan Search

RQ1 general: what activities should the libraries prioritize, preferably with low effort and high impact, which will improve access to their collections as data in Japan Search and Europeana?
RQ2 specific to data models: What are the most important fields in the data models and what requirements do they set for the improvement of metadata and the use of linked open data in an institutional setting?