Nice
There main difference in clip and grow techniques between alternate leaf trees and opposite leaf trees is that with alternate leaf trees, you normally prune back to leave at least 2 or 3 leaves, or leaf buds, to allow ramification to increase. If you pruned an alternate leaf tree back to a single leaf (node), there would be only the change in direction from the new bud, but no increase in ramification.
With opposite leaf trees, every internode has 2 buds at the base of the leaves. In this case, you can let the tree grow out, then prune back to leaving a single node of extension, and you will get 2 branches.
Some trees, like azalea will produce multiple. buds at a node, especially immediately below a spent flower. With all, regardless of pattern, if you end up with more than 2 branches at a node, you prune back to no more than 2 branches at each node.
Shaping, or styling a bonsai. It is normal in the lower half of the tree, that the "front" of the tree will have fewer branches, thus leaving the trunk line exposed. So a "hole" on the front side, if used to expose trunk to view, is a good thing. However, if the "hole" does not line up with the trunk, in other words is just negative space, that might be good, might be bad. Holes can often be filled with allowing branches in the back to grow to one side or another to fill in holes from behind.
I can't tell how with the photos you posted. In person I would be able to see better. The fact that in your photos foliage seems dense and well distributed I don't think you have any "serious holes".
