(the cloud storage is meant to come back any day?)
Most apps have an internal sqlite db, with adb root you can pull it. Path is always slightly different, but same pattern, see also Tasks and other accounts - #8 by tcecyk
adb pull /data/data/foundation.e.notes/databases/OWNCLOUD_NOTES
echo "select * from Note;" | sqlite3 -csv OWNCLOUD_NOTES > notes.csv