Māna: Conceit
Conceit is the habit of measuring yourself against others. Being made inferior to the rest of the assemblies is a ranking, and the sting is that Corinth came out low on the list. Neighbors comparing houses over the fence feel the same ache, which comes from the measuring itself and works the same whether you land above, level, or below.
Subharatā: Being easy to support
Easy to support describes a person who lives light on the people around him. Paul working his own trade so his hands cost them nothing is that quality in practice, the traveling teacher who leaves the pantry as full as he found it. Among monks this counts as a virtue; in Corinth it landed as an insult, because the people who fed the other assemblies wanted the same claim on him.
Dāna: Giving
Giving ripens first in the giver. A household that is never asked for bread never gets to hand any over, and the warmth of that handing over was what Corinth lost when he refused to be a burden. Underneath the wounded pride their complaint holds something fair: they were kept out of the one exchange they were ready for.
Dhammadāna: The gift of the teaching
The gift of the teaching outweighs any gift of goods. Corinth received that gift in full and paid nothing for it, which is precisely what left the books looking lopsided to them. Support going one way and teaching coming back the other is the ordinary arrangement between a teacher and the people he serves, and he worked only one side of it.
Khamā: Pardon
Pardon is a thing asked for and granted in plain words. "Forgive me this wrong" shrinks the whole grievance down to one small nameable item, an offense that can be set down instead of nursed. Monks settle a quarrel by saying much the same to each other's face, and even said with a raised eyebrow, as it is here, the words still hand Corinth a way to let the matter go.