Source Sans Pro has been updated a few hours ago, and it now includes Cyrillic, Greek and IPA characters, as well as several corrections to diacritics, more punctuation, and the new Russian ruble sign. https://github.com/adobe/source-sans-pro/releases/tag/2.010R-ro%2F1.065R-it
Now the announcement is live: http://blog.typekit.com/2014/07/09/source-sans-v2/
Andras Timar committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/core/commit/?id=e842914ae3ec6109e889cfc4d0387192a68d2907 fdo#81095 update our copy of Source Sans Pro The patch should be included in the daily builds available at http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: http://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.
Andras Timar committed a patch related to this issue. It has been pushed to "libreoffice-4-3": http://cgit.freedesktop.org/libreoffice/core/commit/?id=e343f9c570a6d038019bea1377b50d5f6b081a86&h=libreoffice-4-3 fdo#81095 update our copy of Source Sans Pro It will be available in LibreOffice 4.3.1. The patch should be included in the daily builds available at http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: http://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.
Thank you very much, András. :-)