For an unknown reason the Ukrainian.nsh file of NSIS 3 misses the entries
!ifdef MULTIUSER_INSTALLMODEPAGE
${LangFileString} MULTIUSER_TEXT_INSTALLMODE_TITLE
${LangFileString} MULTIUSER_TEXT_INSTALLMODE_SUBTITLE
${LangFileString} MULTIUSER_INNERTEXT_INSTALLMODE_TOP
${LangFileString} MULTIUSER_INNERTEXT_INSTALLMODE_ALLUSERS
${LangFileString} MULTIUSER_INNERTEXT_INSTALLMODE_CURRENTUSER
!endif
I added them in the attached patch and the Ukrainian translator Yuri Chornoivan of the GPLed program "LyX" translated the messages. He agreed to send you this patch.
The attached file is in UTF-8.