Trying to keep the 3d template light , I did some experiments to make the 3d template look better but most of my attempts was not good .
I noticed that different setting looked best on some type of images and some other did not.
So, I am thinking of
a) putting different 3d templates or
b)using a signle template that takes parameters (eg something like index.php?enemy_transparency=70&gold_transparency=100).
About your modification of the template: I see you added many enemies. If you want to create a similar engine you might want to use an array for enemies. It will be simpler to handle.
For A.G.E. -at this point- , I believe 3 enemies are enough.
Also, you could check the color transparency demo here : https://plirof.itch.io/age-ascii-game-engine/devlog/1145749/demo3d-4005a-transpa...
For enemies you could edit their images and put them on a specific color backgound and then use the above demo file.