As for RuMiNa,
>Climate
The entirety of RuMiNa has the same climate classification, namely humid subtropical climate (Cfa). That means its hottest month averages above 22℃, and its coldest month averages above freezing. It has no pronounced dry season, and the warm ocean current off its coast means the climate will be relatively humid across the year. Overall, it is a fairly temperate place, where snow is uncommon but not unexpected in the north. Be noted that Cfa is a somewhat broad climate zone, though, and it applies to places that many people would not consider to have the same climate. Overall, I would say from north to south of RuMiNa, the climate would be similar to US East Coast from New York to... around South Carolina? In East Asia it would be similar to southeastern China from Shanghai to around Fujian. It does not really occur in Europe, but the closest would be from northern Italy to a hotter northern Italy. You can also think of it as a hotter western Europe.
>Biome
Like the examples listed above, the original biome of RuMiNa would be forest. Specifically, it is likely to be dominated by seasonal broadleaf forest, meaning that most trees there have broad leaves that are shedded during the cool winter. In some places, local topography and (more importantly) human intervention could change the biome into grassland (which includes farmland, since most food crops we grow are technically some kind of grass.
>>40670165
Oh. Alright, what if we keep the landmass (maybe move it a bit north to make it not as hot) and then discuss whether to add the islands for RuMiNa separately?