Hi Gergo,
I'm not sure if you want to localize just the portlet, or if you mean to localize the entire site (including the portlet). I'm not familair with JSF, but your configuration certainly looks correct. I know that it is possible to change the default language, as well as configure the supported languages in either the portal-ext.properties file or in the Control Panel.
If you want to set the default language for the site in the control panel, then go to --
Control Panel > Sites > [Your Site] > Configuration (section on left) > Site Settings and then choose "Display Settings" from the sub menu on the right. In there you can choose "Define a custom default language and additional available languages for this site." and then set the default language and supported languages. Once you have done that, it should pick up your file.
If you wish to do it via portal-ext.properties then it would be applicable server wide (all sites I believe) and the properties you would override are --
#
# Specify the available locales. Messages corresponding to a specific
# language are specified in properties files with file names matching that
# of content/Language_*.properties. These values can also be overridden in
# properties files with file names matching that of
# content/Language-ext_*.properties. Use a comma to separate
# each entry.
#
# If there is more than one locale for the same language, the first one in
# the list will be used when a translation is requested in another locale of
# the same language but a translated value cannot be found. For example, if
# there are two locales such us pt_BR and pt_PT (in this order), any key not
# found in pt_PT will be looked for in pt_BR.
#
# Language codes follow the ISO 639-1 standard. Content for each locale must
# be UTF-8 encoded.
#
# See the following links, which specify language and country codes:
# http://www.loc.gov/standards/iso639-2/php/code_list.php
# http://userpage.chemie.fu-berlin.de/diverse/doc/ISO_3166.html
#
locales=ar_SA,eu_ES,bg_BG,ca_AD,ca_ES,zh_CN,zh_TW,hr_HR,cs_CZ,da_DK,nl_NL,nl_BE,en_US,en_GB,en_AU,et_EE,fi_FI,fr_FR,fr_CA,gl_ES,de_DE,el_GR,iw_IL,hi_IN,hu_HU,in_ID,it_IT,ja_JP,ko_KR,lo_LA,lt_LT,nb_NO,fa_IR,pl_PL,pt_BR,pt_PT,ro_RO,ru_RU,sr_RS,sr_RS_latin,sl_SI,sk_SK,es_ES,sv_SE,tr_TR,uk_UA,vi_VN
#
# Specify the locales that are enabled by default.
#
locales.enabled=ca_ES,zh_CN,en_US,fi_FI,fr_FR,de_DE,iw_IL,hu_HU,ja_JP,pt_BR,es_ES
#
# This sets the default locale of the portal, overriding the properties
# "user.language" and "user.country" specified in system.properties.
#
#company.default.locale=en_US
