For Thunderbird you will want to install the thunderbird-locale-sv package. For Evolution I'm not sure, but perhaps make sure you have both the language-pack-sv and language-pack-gnome-sv packages installed, as the translations may be included in that for Evolution (which is a GNOME project). Below are all the Swedish language packages I could find, perhaps some there will also interest you.
Code:
aspell-sv - Swedish dictionary for GNU aspell
calligra-l10n-sv - Swedish (sv) localization files for Calligra
cfi-sv - Copyright finns inte, book about hacker culture
childsplay-alphabet-sounds-sv - Swedish sound files for childsplay
firefox-locale-sv - Swedish language pack for Firefox
gcompris-sound-sv - Swedish sound files for GCompris
gimp-help-sv - Documentation for the GIMP (Swedish)
kde-l10n-sv - Swedish (sv) localization for KDE
koffice-l10n-sv - Swedish (sv) translations for KOffice
language-pack-gnome-sv - GNOME translation updates for language Swedish
language-pack-kde-sv - KDE translation meta package for language Swedish
language-pack-sv - translation updates for language Swedish
libreoffice-help-sv - office productivity suite -- Swedish help
libreoffice-l10n-sv - office productivity suite -- Swedish language package
lifelines-doc-sv - swedish documentation for lifelines, a genealogy software system
thunderbird-locale-sv - Swedish language pack for Thunderbird