похоже, что вы пропустили запятую после MAX(h.edition)
SELECT b.mc_boxes_idmc_boxes,
t.idtitles,
t.title,
t.languages_idlanguages,
MAX(h.idtitle_history),
MAX(h.edition),
(SELECT h.preview, h.file WHERE h.idtitle_history = MAX(h.idtitle_history))
FROM mc_boxes_has_titles b
LEFT JOIN titles t ON b.titles_idtitles = t.idtitles
LEFT JOIN title_history h ON h.titles_idtitles = t.idtitles
WHERE b.mc_boxes_idmc_boxes = 12
AND h.edition IS NOT NULL
GROUP BY b.mc_boxes_idmc_boxes, idtitles
ORDER BY b.sortorder;
кроме запятой, вы выбираете два поля в своем подзапросе
SELECT b.mc_boxes_idmc_boxes,
t.idtitles,
t.title,
t.languages_idlanguages,
MAX(h.idtitle_history),
MAX(h.edition),
(SELECT preview FROM title_history WHERE idtitle_history = MAX(h.idtitle_history)),
(SELECT [file] FROM title_history WHERE idtitle_history = MAX(h.idtitle_history))
FROM mc_boxes_has_titles b
LEFT JOIN titles t ON b.titles_idtitles = t.idtitles
LEFT JOIN title_history h ON h.titles_idtitles = t.idtitles
WHERE b.mc_boxes_idmc_boxes = 12
AND h.edition IS NOT NULL
GROUP BY b.mc_boxes_idmc_boxes, idtitles
ORDER BY b.sortorder;