Hello Aternos team,
I would like to suggest the mod "Eternal Winter". It's an addon for Tough as Nails and should improve the difficulty for some servers.
It lets snow fall in all biomes and is highly configurable, thankfully.
It supports 1.12.2, 1.12.1, 1.12, 1.11.2, 1.11, 1.10.2, and 1.10.
Here is the curseforge link: https://minecraft.curseforge.com/projects/eternal-winter