I understand.
And I must say that I like the screen merging with transparency you've done
I wil ltake a look to your repository to understand how you achieve this feature.
Concerning AGA support I'm currently working on a try to make a "native support to AGA chipset" to AMOS.
I managed to make Dual Playfield works up to 2x 16 colours screens (fully AMOS native) by modifying the AMOS Professional ASM 68000 source code.
It gives nice results (see my post in this forum).
my work on AmosPRO Source code is also available in a git hub repository I've made
Regards,