After Killing a trader llama while beeing in group pillagers would stop Moving and fire at the same location as they were before the target was killed, even if it means shooting at another pillager and Killing him. They eventually stop if presented with a villager traderllama or wanderingtrader( if they see him).

(In this case the pillagers were spawned with eggs on a flat map i dont know if it is any different with naturraly generated pillagers.)