I like the spacing as is.
I like the use of moss.
However, I would have personally opted for a slightly wider pot, a little shallower, and not have "mounded" the planting.
I think the main tree is potted too high.
Most of the trees have too thick of upper branches, ruins the overall perspective of the piece. The main piece has some upper branches that appear thicker than the lower.
The trees on the left and right lean perfectly natural. The rear tree however looks like it was bent to the left simply to fill in a space, this should be a little straighter or maybe the bend starts a little too low.
About 2/3 of the way up, there is a tangled custer of branches from three trunks that catches and holds the eye.
With some tweaking and ramification, this could be a very nice group.
Nice seeing it.