And that is my point, the main advice given when setting up a communal of pokies is to keep the space confined.
When the spiders start maturing and the space becomes less the start killing each other. the attempt ends with one big spider or the person spiting them up before he loses he's beloved communal spiders.
Giving the spiders space (as you have done) will allow the spiders to move around as they please, they are not forced to live on top of each other. I'm sure you don't have to "tell" them by forcing them into small confined tank that they will be communal, the spider will know, smell, feel that they are not alone in a tank.
I think this kind of forcing is not good, even the H.incei communal will kill off if the space becomes to tight.
And as you have said in your thread there seems to be groups forming.
As they grow so will their webbing, and they will move away from each other.
But curtain species will reacted differently and do well in a communal where other will not, it is to find what each sp needs to be housed in.