Re: [S] Neighborhood houses without snow on the roof
I can also confirm with 100% certainty that this bug still occurs in a modless, CC free save file.
From what I have been able to gather, the snow does not accumulate whatsoever on certain world decor buildings mainly in Willow Creek and Newcrest.
(Foundry Cove, Willow Creek)
(Crawdad Quarter, Willow Creek)
(Llama Lagoon, Newcrest)
And as you can see from the following image, the problem also occurs - though in a smaller number - in Brindleton Bay as well. They even appear to be the same world objects as in Foundry Cove!
(Cavalier Cove, Brindleton Bay)
I did check around other worlds that are meant to have snow accumulation (though I do not own ALL the packs that come with worlds) and it appears that outside these base game specific world decor objects, only Windenburg had a similar issue.
However, in Windenburg there was indeed snow accumulation occuring on the decor houses, but some clearly had more than others.
(Olde Platz, Windenburg)
I am not sure if the Windenburg issue is an actual bug, or just an oversight, but the picture was taken in the middle of a blizzard, so it does seem weird for some of the decor buildings to not get the same full blanket of snow as the others.
Willow Creek and Newcrest are definitely bugged, though.
If you take a look at the official trailer for The Sims 4: Seasons, you can see the background decor buildings covered in snow, which confirms that it was not always like this.
(This short section in the trailer appears to be in the same neighborhood as in the first image.)