Unfortunately, I think you'll have to stick with the current theme for your Samsung S4. I know you did not like the invert function, but I use it on my iPhone and for me it is incredibly helpful. I believe, just like the iPhone, you can enable a shortcut for all the accessibility options you need at a quick press of a button. So, to avoid the the screen from staying inverted, which ruins pictures, videos, and basically anything unless it's black text on white background, $1. So, how I use this (for iPhone equivalent) to my advantage is, if I am struggling to read my texts, a website such as Wikipedia, the Facebook app, et cetera which all have black text on a white background, I quickly invert my screen with the shortcut (and zoom in if necessary).

I use invert all the time, so I hope knowing how to make it into a shortcut so you can invert or un-invert at free-will will help you. I don't think their would be a theme easily available that will have a white text on a dark background. I had a Sony Xperia and I had to sell it as when I updated the Android OS, the theme had completely changed to black text on transparent, light colour backgrounds and I could not see it at all to read my texts and that phone didn't have any good Android accessibility options. So, I know the struggle lol.