TB:
First, you are right about this not really being a truss. Just a way of mitigating rafter thurst by shunting the bulk of the load down to the dropped tie beam, and then to a post in the middle of that tie beam. It's critical that your queen/collar arrangement do this. If the joinery is not executed correctly to give you solid bearing surfaces, or not designd to take shrinkage into account, then the load will shift to the rafter feet, which will push out on the post tops, which act as a lever to pry apart the tie-to-post joint. CB.
