Karuṇā: Compassion
Compassion is the heart's stirring at another's pain. Bringing many children to glory is the entire purpose of the labor here, and the one doing the leading gains nothing he was missing. A Buddha whose own work is long finished still walks dusty roads for forty-five years teaching whoever will listen, moved by the same thing.
Bodhisatta: A being bound for awakening
A bodhisatta is someone still in training for full awakening. Every Jātaka birth in which the future Buddha gives away wealth, children, and his own flesh is another stretch of that one road. Perfect through sufferings describes exactly this: capacity gets built under load, the way a rope is tested with weight before anyone trusts it to hold.
Dukkha: Suffering
Dukkha covers pain, loss, and the ache in anything that will not stay. Sufferings in the plural means the ordinary kinds: hunger, betrayal, fear at night, a body that breaks. The Pali path runs straight through these with open eyes, which is why someone who has felt them all the way down can be trusted by those still inside them.
Pāramī: The perfections
Pāramī are qualities carried to their fullest reach: giving, patience, truth, resolve, and the rest. Made perfect points at completion, the way a house frame stands sound long before the roof goes on. Each one gets finished under pressure; patience has no edge until someone strikes you, and resolve stays untested until the road turns hard.
Magga: The path
Magga is the road itself, set out in eight factors. Author of their salvation carries the sense of one who goes first and leaves the way open behind him; the Buddha told of finding an ancient road overgrown in the forest, following it to a ruined city, then coming back to report where it runs. Someone has to break the trail before anyone else can arrive.
Dhammadāyāda: Heir of the Dhamma
Dhammadāyāda names one who inherits the teaching itself. Many children brought to glory are kin by that kind of descent, born of the Dhamma and receiving what the elder already holds, and the next line follows naturally: he is not ashamed to call them brothers. The inheritance is a capacity to walk the same road to its end, and it grows rather than divides as more receive it.