problems

Have you installed and loaded the Style-Files?

Folder ~/.gimp2.8/plug-ins/CalendarCreator/

in my case there are following files inside:

names_dots.txt STYL_clear STYL_orange STYL_test
names_gimpchat.txt STYL_clear_version2 STYL_pastel STYL_windows
names_horizontal.txt STYL_default STYL_table
names_vertical.txt STYL_gimpchat STYL_table_note
OknoDialogowe.glade STYL_medium STYL_table_small

At the moment the deprecated warnings could be ignored.

What happens if you change opacity to full?

My system is 64 bits, maybe 32 bits need some other fix ?!