I doubt they would go there. In fact, this reminds me of the argument that Marina and Pearl was an inkling-octoling hybrid because their top teeth are different from normal inklings, despite the fact that though octolings have never illustrated that trait in their top teeth. Pearl, Marie and Callie have different eyes than the playable inklings. Similar to the more realistic beaks that Pearl and Marina have, those eyes makes them stand out compared to the playable inklings while also sticking more closely to real world anatomy. Marina has special eyes compared to the playable Octolings likely for the same reason. Regarding the eyeliner point, Marina has black eyeliner. The purple eyeliner in the concept art for Splatoon 1 is coupled with green irises, overall matching the style of all octarians affiliated with DJ Octavio. And the octopus forms of the Octoling in S1 have green sclera surrounded by purple markings, just like other Octarians and DJ Octavio. I doubt this is a general trait of all Octolings especially considering how Marina bucks the trend in her white sclera, darker skin, black eye markings, and ability to adopt different colors.