Please allow customization of colours for progress bars in Project Overview. I kinda dislike new colours in Lokalize and prefer colours as shown in http://i18n.kde.org/stats/gui/trunk-kde4/team/ That gradient looks cool, too. Maybe if you could add gradient, default colours to above mentioned page and let them be customizable? Reproducible: Always
Note that Lokalize uses the colours from your KDE colour scheme (the positive, neutral and negative colours). So it is *already* possible to customise the colours; you just have to modify your KDE colour scheme (System Settings → Colours), or select another colour scheme.
As Karl said, this is already possible through system-wide settings.