In the anime, whenever Kakyuu speaks to the Three Lights, she only ever addresses them as "Starlights", "Fighter", "Healer", etc. She also questions their Earth civilian forms in episode 194:
Kakyuu: "Fighter. Do you use that appearance on Earth?"
Seiya: "Oh... to find the only lady here, this was more convenient."
Implying that their Kinmokuseijin forms are not like that of their Earthling forms.
Their Senshi forms might even be their standard forms on Kinmoku, since Kakyuu doesn't use any other names besides those ones, whether they're in Senshi form or not.
At a later point in the same episode, Seiya refers to himself ("This is my last moment as Seiya Kou...") as though "Kou Seiya" wasn't even a real person and just a pseudonym or false identity altogether.
Earlier, in episode 189, after learning each other's identities, Minako seems convinced that their Starlight forms are their ture forms, as she says, "It’s shocking that Three Lights are girls!"
aDam said:
Like in Beast Wars when Tigertron spends too much time as a tiger he starts to get feral.
Um... no. Tigatron did not become any more feral than the other characters by staying in his Beast Mode longer than normal. Quite the opposite, in fact. He
embraced his animal half, bypassing the block within his programming that prevented his two forms from acting in unison. Whereas, when the other Maximals were stuck staying in Beast Mode for a prolonged period of time, they
did become more feral due to this programming block, as their animal instincts began to dominate their rationality and intellect. Only after Tigatron guided them back to sanity did they learn to delete this block and unite their inner beasts with their robot selves.
He remained tame and coolheaded in his Beast Mode, whereas the others just went wild.