If you are noticing that downloading Serum presets from the Splice app aren't showing up in Serum, it's likely the Serum presets are saving to your Splice folder instead of the Xfer presets folder.
Here is how to solve this:
Install the Beta Version of Splice Desktop v5.2.5 depending on your OS:
Mac: Download here
Windows: Download here
Once updated, new presets will save directly to your Serum presets folder.
Move Existing Presets
To move presets already saved in your Splice folder:
Locate the presets in your Splice folder (Where is my Splice folder?)
Drag them manually to your Xfer Serum presets folder.
Default Serum Preset Locations:
Windows:
C:\Users\USERNAME\Documents\Xfer\Serum Presets\Mac:
[user]/Macintosh HD/Library/Audio/Presets/Xfer Records/Serum Presets/Presets