The word kam-numaa with the meaning of 'rarely visible', 'visible with difficulty', seems to be Mir's own invention, because it isn't in the dictionaries. Since the word kam is also used for absolute negation, the meaning of kam-numaa can also be 'absolutely not visible'. And since the meaning of numaa can also be 'showing' (as for example jalvah-numaa means 'showing jalvah '), the meaning of kam-numaa can also be 'showing things to be petty or foolish', or 'showing oneself to be petty or foolish'.
With regard to all these meanings, in the second line :zaahir hai is very fine. Then, notice that in the first line it's a question of only one heart; this can be the speaker's heart, or whoever's heart, but it's only one heart. In the second line, with the phrase jo ko))ii us ko chaahe he has advanced the theme. That is, with jo ko))ii he has made the utterance non-individual and generalized, and has also created the implication that perhaps her desirers are numerous. And it should also be kept in mind that he has called the heart desirous of her-- he hasn't contented himself with her glory/appearance or the sight of her.
Similarly, in the second line too he has said 'might desire/want her'-- that is, the desirer definitely wants a sight of her, but wants something more as well. Thus even if the kam-numaa beloved would make herself apparent, the desirer's condition, or that of the heart, would definitely remain alienated. Because first of all it's useless to have the sight alone vouchsafed, and even if the sight is obtained then nothing has been obtained beyond it.
Abd ul-Rashid has given an example of the use of kam-numaa in Vali; thus the honor of primacy goes to Vali:
kam-numaa hai nau-javaa;N meraa bah rang-e maah-e nau
maah-e nau hotaa hai ak;sar ai ((aziizaa;N kam-numaa
[he is little-apparent, my youthful boy, in the manner of the new moon
the new moon is usually, oh dear friends, little-apparent]
But Vali's theme is very commonplace, and the meaning too is very little.
