• mṛga-tṛṣṇām — a mirage (lit. 'deer-thirst')
  Classical Indian image: the gazelle running to water that is not there. Used here for material assets — the more you chase, the further they retreat.
• bālāḥ — men of childish intelligence
  Not children in age but in discrimination — viveka-rahita. Gauḍīyas use bāla for those who, lacking guru, mistake reflections for substance.
• vaikārikīm — subject to transformations
  Vaikārika — that which undergoes vikāra, change. Māyā is defined by mutation; the kings here name the philosophical reason it cannot be vastu.
• ayuktāḥ — those lacking discrimination / yoga
  A + yukta. The yukta is one whose intellect is joined to Bhagavān; the ayukta sees māyā's mutations as substance because he is not connected to the only thing that does not mutate.
• vastu — real substance
  Vastu in Vaiṣṇava usage is reserved for that which is svarūpa-siddha — self-establishedly real. Only Bhagavān, His dhāma, His associates, and bhakti qualify.

• What mirage am I currently working toward?
• What would training my eyes to see Māyā as Māyā require?

A child running across hot sand sees water shimmering ahead and runs faster, never reaching it, never doubting it. So the irrational mind, says the verse, races toward māyā's transformations and never asks why the pond keeps receding.