@Walter_vi_britannia I'm pretty sure that's not how it works. As Banarok said, she simply slaps an image based on what she hears, like when Mana was thinking their friend "was working" without further context, Nakano pictured him carrying boxes because that was her own interpretation of the job (reality was he worked fixing bikes).
Since people mostly think in their own language, even if Nakano could read a foreigner's mind she'd likely be unable to understand anything and they'd be text-only bubbles; she can't fill in the gaps with images if she can't even comprehend the "text".