This is another case of FFXIV using title case for certain things and sentence case for others. Leynodes, like aetherytes, are not capitalised naturally. Similar things happen with "the outskirts" outside of the Everkeep. It's just the English localisation using title case for toast/notifications/menus/name text, and sentence case for, well, sentences. I think they use title case too much personally. I would much rather Things kept natural sentence case structure most of the time.