1) have a priorities list for highlighted genres. Say, if I have both Romance and Horror highlighted, I could choose which color I want to be shown over the other (say, romance over horror), so that any manga with both would be highlighted as romance.
2) instead of highlighting the whole line on the releases page, have a little circle or something off to the side of the title that is like a pie chart that shows all the colors in wedges. (I fear this may be really complex.)
3) similar to #2 but probably easier, next to the title, have multiple boxes of colors for the genres. For example, there would be a title that has Romance (red), fantasy (yellow), and shoujo (blue). there would be a red box, then a yellow box, and then a blue box.
4) if the manga were somehow categorized into main genres and sub-genres, that could also solve the problem. There could be a poll for each page where the readers vote on which genre they think is the main genre of the series, which could provide a sort of ranking/relevance order for the genres. Whichever highlighted genre is listed as higher or more relevant would then take precedence over the other highlighted genres attributed.
I think 1 and 4 would be easier, but they also introduce more problems than 2 and 3. I know there are some manga that only a few people have read and would therefore only have a few who could vote, and some where two genres are equally the forefront genre for a series.
Again, I have no idea how difficult or complex these features would be, but they are only suggestions.
Feel free to add more suggestions or list problems/fixes you see regarding my suggestions! I'm all about constructive criticism
