Yes, that is the actual returned value. But
is not valid JSON (see 2.5 in rfc4627). And I don't think invalid JSON *should* be expected from a function called COLUMN_JSON.
But I don't know what Maria should do when it is asked to return a value in a format that cannot express that value.
I get the result (what I think is expected) from the query "
SELECT COLUMN_JSON(COLUMN_CREATE('name', UNHEX('C1C2C3C4C5C6'))):"
{"name":"ÁÂÃÄÅÆ"}
.. in SQLyog (GUI client always using UTF8 as client character set) on Windows. In command line client shipped with MariaDB 10.0 for Windows, I get garbage (both after SET NAMES latin1 and SET NAMES utf8 - but MariaDB does not (yet) have a fully unicode-enabled commandline client for Windows like MySQL 5.6 and 5.7 have).
Are you sure that your client environment will handle all those special/accented characters at the same time? I think you bumped into an encoding issue in the client of some kind. What is your client environment and OS, and what does the query return here?
-- Peter
-- Webyog