Perhaps more than any other creature here, gnomes have filled a wide variety of roles across RPG settings. Some cast them as tricksters, others as bumbling inventors and eccentric wizards, others as bardic tale-weavers, others as helpful but reclusive fairy folk.
Ultimately, this shifting identity the major reason gnomes don’t, by default, appear in Escarnum‘s world. If you wish to bring them back in, their natural place depends on which version you enjoy.
Inventor-gnomes would be a good fit for the bizarre wizard-silicon-valley of Independence proper, or perhaps underground digging for Precursor relics. Fairy and trickster gnomes would be strongest in Deepwood, and other places where the border with the Feywild stretches thin. Bardic gnomes might even be travellers from Aethys, or beyond.
Alternatively, if you stick to a gnomeless Escarnum, most of their various roles are filled by the various clans of kobold, especially that of inventors. Alternatives include felbraug, for magic-using gnomes—a felbraug’s psychic nature and small stature make it a good replacement. For bardic or trickster gnomes, the abilen is a fair substitute, possessing comparable social grace and small size.