Relates to: MC-176095 MC-199660 MC-208679 MC-250985
May also relate to: MC-159560
The bug
Much like is the case in MC-266280, the textures for leather armor contain pixels that, while definitely within the region mapped to visible areas, are nonetheless impossible to see under any circumstances due to being obscured by an overlay texture. As such, these overlapped textures can be deleted from the texture file entirely with no visual difference, lowering the file size.
How to fix
An easy fix - just replace the vanilla leather armor texture files with the ones attached, and replace Programmer Art's with the fixed Programmer Art textures as well.
I think most of the edits you made are good ways to reduce bytes but that is like, just a not ,