Was about to say this. When this happens, a couple things could be the source:'Proshia' castle? Wasn't it Prussia or something like that before? This and some of the characters names changing is making me wonder what's with the inconsistencies with the recent chapters.
It wasn't updated for years. The WN and its translation stopped quite a long time ago, and i'm not sure why and if author having LN. Judging by the raws how manga concluded (about in the same arc) author doesn't touch WN for all that time and translators miss/forgot/dropped isn't valuable. The only noticeable difference between WN and manga: WN doesn't have final 'Boss Battle' and as a result noticeable conclusion, novel only reveal 'this arc villain'.By the way, is the source material still going?