Is there any localization project going on? I would volunteer for Czech language Actually i dont need localized browser for myself, but i think, more people would consider using Vivaldi, if it was localized. And i think you would easily get volunteers for every language. IMHO people are eager to find some old-Opera-like browser.
I just commented on a topic about translation of vivaldi.net : https://vivaldi.net/forum/suggestion-box/236-the-official-translation-localization-thread?start=20 but again, if there's a need for a Polish translator, I'm eager to help.