for me it's easy to imagine where elderwood kindred would fit lore-wise, because i feel like the "Elderwood" skinline isn't only just protectors and overseers of nature as a whole, but superior spirits of the seasons as well... a sort of Council of Nature:
-Elderwood Leblanc is clearly a fairy queen of some sort and would represent Spring: this season depicts well the rebirth and regrowth of nature from winter (in her recall she makes vegetation and flowers sprout and pop up), the whimsycal and joyous mannerism of fairies and is often associated with illusions... the skin colors also match the palette of spring flowers and nature
-Elderwood Hecarim seems like a treant centaur, and would be Summer: it represents strength of nature and life, and most of the creatures that inhabit the forest are most active in this season, which is why he is rapresented as a tree-like centaur, to convey the strenght of not only plants, but beasts as well... in his recall also he makes plantlife grow lush and full of life, like in summer. the skin colours also match with the season
-Elderwood Bard appears as an older tree-like kind of entity, and would be Autumn: not only his appearance fits the bill with his bark on the grayer side, his tunic colours on the cold blues and his beard made of red autumn-like leaves, but also because in this season nature starts to slow down and approach the end of the cycle. spirits gather in the forests, and the mysterious Bard wanders around caretaking nature until Winter comes, with it's unscrutable methods
so in the end only Winter remains... the final step of nature's cycle... Death... all living creatures must die: they are born (Spring), become strong (Summer), grow old (Autumn) and eventually meet their end in the snowy unavoidable clutches of winter... whether you decide to embrace the inevitable and let the cold needles take you peacefully, or fight and suffer the agonizing frostbites, you die nonetheless... but that's not the end of all life, only what reached its end, like weaker plants, dying animals or the like... afterall when winter ends there is always another spring...
Elderwood Kindred as Vegacolors depicted is amazing, and i love it, but in my mind it's more like the leaves of Wolf are actually snow, his mask made of dead and black branches, but actually pretty definite, and Lamb as a dark spirit, covered only by the garb in the image, and it's mask of jagged ice (each one wears the mask of the other)...
in the end Kindred fits Winter very well as i explained, but this would mean that the Elderwood skin-line is complete after them... or maybe the cycle starts anew, who knows, mine is wishful thinking really...
also as Eclipse Leona is coming out, her interactions with the elderwood appear to me as they are part of a group, or at least work for an entity called "Elderwood": "Minstrel of the Forest" (Bard), "Guardian of the Elderwood" (Hecarim) and "Sylvan Conjurer" (Leblanc)... she also says "I claim no quarrel with the Elderwood"... and death blossom apparently is a corrupt version of the more "pure" Elderwood...