Hi Christopher,
Thought I might add my comments to try to clarify the situation.
As Zuzu has already said,
Hosta kikutii var. yakusimensis is now a synonym for
Hosta sieboldiana var. sieboldiana.
The Catalogue of Life literature references for
Hosta sieboldiana var. yakusimensis (1932) and
Hosta kikutii var. yakusimensis (1940) are the publication dates of those names. If you look closely, the latter references exactly the same publication as your link
http://www.hostalibrary.org/sp... (which also mentions the 1932 name as a synonym). So far, no disagreement between the Hosta Library and COL.
As Zuzu has already pointed out, though, the Hosta Library document is dated 2010 and the COL update is 2017. From this we can conclude that between 2010 and 2017
Hosta kikutii var. yakusimensis was merged into
Hosta sieboldiana var. sieboldiana. The COL uses KEW's World Checklist of Selected Plants as its source for this genus; as you can see,
Hosta kikutii var. yakusimensis is no longer accepted; instead, it is a synonym for
Hosta sieboldiana var. sieboldiana. The details given indicate that this change was published in 2016 in the Flora of Japan.
