• śabdam — the sound
  Sound. Gauḍīya: śabda is a tan-mātra; demons and devotees are equally awakened by sound, but to opposite ends — kīrtana-śabda awakens prema, fruit-fall-śabda awakens greed. The same sense, two destinations.
• niśamya — hearing
  Absolutive of ni + √śam (to hear attentively). Gauḍīya: niśamya is the same verb used for the devotee hearing the Bhāgavatam; Dhenuka hears the fruit-fall with the same attentiveness a bhakta gives to hari-kathā. Hearing-direction defines hearing-result.
• asura-rāsabhaḥ — the demon in the form of a jackass
  asura + rāsabha (ass, donkey). Gauḍīya: the body of an ass for an asura is a karmic precision — the dispositions of obstruction and stubborn braying find their matching form. Saṁsāra fits the bottle to the wine.
• abhyadhāvat — ran forward
  Imperfect of abhi + √dhāv — to run toward. Gauḍīya: the same root as dhāvati — to run; demons run toward their destruction; devotees run toward Bhagavān. Same verb, opposite vector.
• kṣiti-talam — the surface of the earth
  kṣiti (earth) + tala (surface). The earth shook under his charging hooves. Gauḍīya: the earth, who in verse 8 was dhanyā for receiving Kṛṣṇa's feet, now trembles under Dhenuka's. The contrast is deliberate — feet that bless vs. feet that frighten.

• What 'demon' has lately awakened in response to a genuine forward move I made?
• Am I reading its arrival as failure when it might actually be confirmation?

A miser hearing his hoard touched comes running like a wounded animal. Dhenuka, hearing the tāla-fruits falling, charges from his hiding place, shaking the earth and trees. The verse is sound-driven — śabdam niśamya — hearing makes him move. Greed has acoustic sensitivity; demons hear what they fear to lose.