LÖVE

I have an awkwardly sized spritesheet that is 18432 pixels wide by 80 pixels tall (my sprites are 384 pixels wide). When I try to load it with love.graphics.newImage, it draws as garbage (two solid bars of pink and white on top of each other). This seems to hold true for any width down to 16512 pixels, while a 16128 pixels wide PNG draws fine. Is there a natural limit to the image dimensions or the number of pixels in an image?

Yep

https://love2d.org/wiki/love.graphics.getSystemLimits
https://love2d.org/wiki/GraphicsLimit#Notes

Yeah. It can vary depending on the GPU. So you might want to either use smaller images, break it into chunks, or have fallback smaller versions. Basically prepare for lower system limits when you can.