I haven't checked all list of course byt

Mid-republican gallic DC are "formed"
LRR gallic Dc are "formed"
Carthaginian Gallic Dc are "tribal" ( except in Italy )
Gallic tribes are "tribal"
Gallic mercenaries in the Syracusan list are "formed"

What is the reasoning  ?

Mercenaries are formed, tribes are tribal. The Gauls in mass that joined the Carthaginians weren't really mercenaries, although there might be an argument for a small number of them to be formed rather than tribal.

Richard

Early Carthaginians : 18 gallic DC allowed should they not be formed ?