Lots of good suggestions already mentioned above. It is very
difficult to diagnose tree problems from pictures alone, unless it is clearly evident symptoms such as common insect or disease signs. I even hate to mention hunches, because without being there to look at everything
, it is too easy to make a wrong diagnosis. Even the description of "red maple" could be in error.
Because the trees were recently transplanted, my hunch is that they simply did not establish themselves well due to many
possibilities. Even the good tree has a stressed top (thin leaves). The "healthy" tree planting site is not ideal - the roots on the left side will have to go below
the retaining wall and then compete with the sod for water/nutrients = stress.
- Were the planting holes properly prepared (dug much wider than the root ball?
- Is the surrounding soil hard construction backfill, impossible for new roots to penetrate?
- Maybe unhealthy trees from the get-go (root bound, failed graft, root ball too small, mismatched cultivar to site,...................................)
- Sometimes ball& burlap rope is left on the root collar and it girdles the trunk
- possibly planted too deep, especially the retaining wall side?
Goodness, just too many things we cannot see from the pictures. Insects, disease, environmental issues, site issues, animal damage, etc.. I would guess that the mostly bare tree will not survive with less than 10% live crown. You could scrape the bark on a few of the bare branches to see if there is green (live) cambium underneath.
Sorry I cannot help more. Your Land Grant University is University of Florida in Gainseville and they have a plant diagnostic center that might be able to assist you: https://plantpath.ifas.ufl.edu/extension/plant-diagnostic-center/