The Zil aren't really tinkerers, they are information-gatherers. Bonuses to Bluff, Haggle, Diplomacy, possibly Listen would probably fit better. (Kinda steps on the half-elf's toes then.)
Here are a couple of options for gnomes ...
-2 STR, +2 CON (gnomes are hardy and hardworking)
-2 STR, +2 CHA (gnomes often have gifts as bards)
They might have bonuses for traps / search / spot, if they're often tinkerers, and they might get some "flavor" bonuses when playing an artificer. Dragonmark feats could focus on illusions, even if that overlaps with elves.
Such as what?
Various profiles can make sense, providing distinctive advantages and disadvantages, when compared to other races.