Hi Perla,
You might consider freezing the cookies. I only use royal icing, but I have frozen intricately decorated and painted cookies with great success. I just package them in cello bags, lay them flat in a covered tray, and freeze. To defrost, I lay them flat on a cooling rack for an hour or two. I've done side-by-side taste comparisons between my fozen and unfrozen cookies, and my "testers" are unable to detect the difference.
I've never used glacé, but I have cookies decorated with royal icing that are three years old and still look just as they did when I made them.
Wish I had more advice to offer. Hopefully someone with more applicable experience will chime in.