Your overthinking it mate.
I am the same, I try to place things nicely and it ends up looking too contrived and unnatural.
I love the smaller Liana with the broms mounted on it, but I feel it is a little small and looks pretty lost in there especially with the thicker Lianas overpowering it.
I would personally use the larger lianas as the main structure and mount the broms on them towards the back then use the smaller liana as an accent towards the front on the side.
I just put together a viv for my Retics and literally tossed the twigs/branches in along with the leaf litter and vine cuttings.
The only thought I put into it was where the broms would go to allow growth and pup space.
Regards,
Richie