So I was thinking about other Radiantspren and what we learned about them in Oathbringer, and then I remebered this little line from Edgedancer:
So Keenspren, I believe, are one of the radiantspren that we don't yet.
There are five types of spren:
Object Spren: The voices of the spheres in Shadesmar
Emotion/Condition/Nature Spren: Like Anticipationspren, Hungerspren, and Windspren. These spren are bascailly the animals of Shadesmar, and behave as such.
Radiantspren: These are the spren of radiants. They populate the cities of Shadesmar and is its civilization.
Voidspren: Spren of Odium
Unique Spren: Spren of immense power, that also have consciousness, and all have unique names: Stormfather, Nightwatcher, and the Sibling.
Wyndle says he made a garden for keenspren, just like he also says he made gardens for honorspren and Cryptics. Which probably means that keenspren are probably radiant spren, unless he made them for animal-like spren.
Keenspren are probably not voidspren because voidspren don't mingle with other conscience spren, and they aren't unique spren because unique spren are one of there type.
That leaves Keenspren to only be Radiantspren making them the spren of a Radiant order.