Forgetting the classic Black Wheel novel, all my observations of the Targoids in the ED lead me to only one thought. They are animals at a fairly average level of development.
I actually think they did a nice job of making the aliens think in an alien way. Their behavior isn't really solo ambush hunter, pack hunter, strictly farmer, etc. Seem to be in long game mode. Their tactics don't change in combat (is this intentional?), their weapons don't seem to evolve. The armor update shortly after AX weapons came out felt really gamey and not really lore based.
Maybe they just prod civilizations into developing defensive AIs which have a pattern of self-terminating the AI creating populations.
Glad they are mysterious.