There wasn't any consensus reached on whether to use the ash colour scheme instead of snow, so I wouldn't include it as the baseline to work off of. It could work as an alternate palette, though obviously more temperature-based tiles like the icicles would be somewhat out of place.
Also, those tiles were more presented as a selection of alternatives to replace all the octagon tiles throughout the set, so again, not really appropriate to stick them at the end there.

In regards to anything at all happening with the set, I don't really think it stands well enough without more tiles. It's completely missing backgrounds, for a start, and the snow tiles could use more variety.

Still though, if it's ever going to be finished we just need more actual content in the set, rather than deliberating on what variation of specific tiles to use.