There is an easy trick to fine someone in Kemono if someone uploaded or not.
Like this link.
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Airv
Is Fantia, and then the ID of the user 164311.
So in Kemono site.
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See how I put Fantia, and then user, then the ID code 164311.
And I'll now give an example of a Fantia account where no one uploaded it yet.
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User Meer@MMD
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If you use the up kemono link, it should take you directly to the main search option instead of a creator, then that means no one uploaded that yet.
You can do this for everything like example
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Shirakami
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So the key is knowing what site they use and what's their ID number for that site.
Hope that helps to find your creators in Kemono instead of using the search which sometimes doesnt search right unfortunately