Germanic Pagans in the North Germanic culture group are nerfed in the pre-Viking Age period because they historically did not have the technology to launch coastal conquests and not the power-base in terms of wealth to do large subjugations. As soon as the Viking Age event triggers though you will get access to bonuses similar to those in vanilla.

Thanks for the quick response. Would be nice if you could force the Viking Age early if you reformed the religion or got to a certain realm size, but I can't expect that much attention to detail to be given to every religious group.