Cyrillic Font issue

Hello All,

When I try to save report in .xls or .pdf file which name contains cyrillic characters, they are shown with strange symbols. You can refer to the attached screenshot.

The report itself contains data written with cyrillic characters and they are shown correct.

Could you please advice me what setting should I adjust and is this OS related problem or it is related to some of the Cognos settings?

The system is: CentOS 5.9 with locale set to bulgarian:

LANG=bg_BG.utf8
LC_CTYPE="bg_BG.utf8"
LC_NUMERIC="bg_BG.utf8"
LC_TIME="bg_BG.utf8"
LC_COLLATE="bg_BG.utf8"
LC_MONETARY="bg_BG.utf8"
LC_MESSAGES="bg_BG.utf8"
LC_PAPER="bg_BG.utf8"
LC_NAME="bg_BG.utf8"
LC_ADDRESS="bg_BG.utf8"
LC_TELEPHONE="bg_BG.utf8"
LC_MEASUREMENT="bg_BG.utf8"
LC_IDENTIFICATION="bg_BG.utf8"
LC_ALL=bg_BG.utf8

The version of Cognos is:

cat cmplst.txt
; Licensed Materials - Property of IBM
; BI and PM: is
; © Copyright IBM Corp. 2004, 2013
; US Government Users Restricted Rights - Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp

[Product Information]

LICENSE_BI_SERVER_version=LICENSE_BI_SERVER-LX64-ML-RTM-10.2.1019.0-0
LICENSE_BI_SERVER_name=IBM Cognos License
SWTAG_BI_SERVER_version=SWTAG_BI_SERVER-LX64-ML-RTM-10.2.1012.0-0
SWTAG_BI_SERVER_name=SWTAG BI Server
C8BISRVR_version=C8BISRVR-LX64-ML-RTM-10.2.5000.275-0
C8BISRVR_name=IBM Cognos Business Intelligence Server

Thank you in advance!