Since the answer appears to be no, I have some advice as somebody working on a low colour-depth (48 colours max on screen) visual novel. If possible, see if you can implement a dithering transition instead of a transparency based one. On anything 1080p or below on a display greater than 12 inches in size will see it's clearly a pixelated effect, but if you render your game at half resolution, the chunky pixels will make it look pretty neat, akin to a PC-98 visual novel.