AFAIK, Valmiki as the writer of Ramayana, is describing the events of Ramayana exactly as the characters themselves perceive and experience those events. So he doesn't add anything more or anything less when he puts into words the thoughts, feelings or actions of those characters.
Given that, when Hanuma starts searching for Sita in Lanka and sees Ravana's wife Mandodari in Ravana's palace from a distance, he mistakes her for Sita because he's never seen Mandodari or Sita before.
And it doesn't appear that Hanuma was told about Ravana or his family by any vanara or rishi. Yet the translator of the following shlokha (51-52, Sarga 10, Sundara Kanda) says Hanuma actually saw Mandodari, in that, he actually knew her name. The original Sanskrit shlokha however only seems to be describing a feature, मन्द उदरीम् (manda udariim = soft-bellied), of the most prominent lady that Hanuma saw in Ravana's palace.
मुक्ता मणि समायुक्तैर् भूषणैः सुविभूषिताम् |
विभूषयन्तीम् इव च स्व श्रिया भवन उत्तमम् || ५-१०-५१
गौरीम् कनक वर्ण आभाम् इष्टाम् अन्तः पुर ईश्वरीम् |
कपिर् मन्द उदरीम् तत्र शयानाम् चारु रूपिणीम् || ५-१०-५२
51;52. kapiH = Hanuma; mandodariim = (saw) Mandodari; charuruupiNiim = with a beautiful form; muktaamaNisamaamuktaiH = together with diamonds and pearls; suvibhuushhitaam well decorated; bhuushhaNaiH = by jewellery; svashriya = and with her self radiance; vibhuushhayantiimiva = as though decorating bhavanottamam = that great building; gauriim = with a fair complexion; kanakavarNaabhaam = and with a radiance like golden colour; ishhTaam = who was dear to her husband; antaHpureshvariim = the lady of the women in that gynaeceum; shayaanaam = sleeping; tatra = there.
Hanuma saw Mandodari with a beautiful form together with diamonds and pearls, well decorated by jewellery and with her self radiance as though decorating that great building with a fair complexion and with a radiance like golden colour, who was dear to her husband the lady of women in that gynaeceum sleeping there. [Shlokha 51-52, Sarga 10, Sundara Kanda]
So does Hanuma really know the name of Ravana's wife as "Mandodari" when he sees her for the first time? If not, is it a mere coincidence that Hanuma spots the predominant feature of Mandodari, which is her soft belly, which also happens to be the reason behind her name?
Is there a better translation of the above shlokha anywhere online that shows the correct meaning of those two words मन्द उदरीम् (manda udariim)?
Also, given that Hanuma hasn't spoken to very many people other than Sita during his search for her, can we assume that, throughout Sundara Kanda, Valmiki is only describing every new character that Hanuma encounters only by their features, but doesn't really refer to them by name in his shlokhas?