The Sylph doesn't farm the Cantaloupe, Honeydew, or Squash blocks from Simple Farming, though she will apply the particles to the 'stem' of those crops. Right clicking the blocks on her, she says she's not interested.

In Enigmatica 6 modpack, MC 1.16.5, Forge 36.2.22, ars_nouveau-1.16.5-1.24.14, simplefarming-1.16.5-1.3.8

Updating: it also doesn't work with cumin/quinoa crops, which aren't placed on farmland but grow as crops. They produce cumin/quinoa 'seeds' as the crop, so I'm guessing they get ignored, even though that's the desired (and only) output of the crop. There's also sunflower crops which produce "sunflower seeds", which also don't work.

If they are classified as forge#seeds, the tag is already set to ignore those. You could remove this tag if you wish to receive all seeds, but that is probably not the full fix you are looking for if you dont also want wheat seeds.