"naive sounding" is a correct and usable phrase in written English.
It means that something in a sentence or phrase sounds naive or lacking in worldly experience. Example: Her statement about love at first sight was quite naive sounding, given her young age and limited dating experience.
We never know for certain whether Mélisande's naive-sounding utterances express innocence or manipulative knowingness.
She even said the song's ennui was tactical: "The point with Virtualism was to recreate a mainstream melody with very naive, teen-sounding lyrics... that sounds superficial and at the same time emotional".
Beirut then flew down to play alongside a "naive, martial-sounding funeral band" - one that essentially comprised "the entire town".
Are the people there, at the risk of sounding naive in several ways, nicer than guests at previous such events?
How do we sustain enthusiasm and belief in this discovery without sounding like naive dreamers or professional salesmen?
How does one criticise China without appearing to have a liberal pro-western agenda, and how does one write positively about China without sounding like a naive apologist?
Yet Mr Farage, a former commodities trader, is no naive Little Englander and UKIP, despite its defensive-sounding name and trademark Euroscepticism and xenophobia, is not an especially British phenomenon.
Said Sarkozy's very French-sounding foreign minister Bernard Kouchner, "Do you think my country would be so naive and shorthanded as to send a 23-year-old woman to spy in Iran?
Pfieffer dances around the whole "grandfathering cluse" thing, and it's sounding more and more like it was always intended as a cover-your-ass safety valve, instead of a naive promise that lots of insurance policies would never change.
