KDE 4.14.2 - American holidays in Digital Clock no matter what

Question

I'm experiencing an issue where no matter what I setup in Digital Clock's configuration, clicking on the clock shows a calendar with American holidays.

From what I understand this is identical to the following bug:

https://bugs.kde.org/show_bug.cgi?id=321459

Enabling/Disabling the "Display Events" option doesn't do anything - the calendar is still showing with American holidays outlined.

KDE's version is 4.14.2, running Debian 8 Jessie with Kernel 3.16.7.

My question is how do I rectify this - I'd like to have Bulgarian holidays, or have no holidays at all displayed there.

BTW, Wishing the US folks a Happy Memorial day beforehand!