Steam is very biased right now and only allowing very popular visual novels to go unchecked on their website. Many other developers are having this problem too. There are other sites that have no problem hosting this material though. If Steam/Valve doesn't bother replying, then maybe you could give these sites a try.
Mangagamer
http://blog.mangagamer.org/...
JastUSA
https://jastusa.com/help/ab...