Environment variables are not correctly mapped to DG parameters when the parameter itself includes an underscore, as is the case with DATAGERRY_Database_database_name. In such cases, the current parsing logic recognizes the parameter as name and the parameter group as Database_database.
This behavior is caused by incorrect regex matching: the expression DATAGERRY_(.*)_(.*) allows underscores in the first matching group. An easy fix would be to limit the first matching group to ([a-zA-Z]*), which works fine with the three current configuration groups. The new expression would be:
DATAGERRY_([a-zA-Z]*)_(.*)