A small bug report... which is not even a bug... but a different side-effect than in vanilla.
When using GIF transparency (on an index different than 0), OXC can still somehow render it transparent, even though it isn't explicitly coded that way.
In OXCE, the "script blit" cannot do that anymore... so mods, which use this "side effect" don't work in OXCE, even though they somehow work in OXC.
The recommendation of course, is to use proper images... but, could you have a look if it would be easy to change the "script blit" to behave the same way?
Attached is a minimod to test it and two screenshots with more explanation.
One easy way to fix it is add script that will ignore 255 value, in may contexts you have value of background color, and instead of drawing new pixel we will draw background again making this effective transparent.
And for not work around solution, no. SDL can this because It create mapping between src and dest palettes. My blit do only 0 check (except for version that run custom scripts per pixel, but this is only when you ask for this). I would need recreate all SDL logic and with this overhead that it will bring.