en_tn/2co/05/12.md

We are not commending ourselves to you again

"We are not recommending ourselves to you again" or "We are not trying to show you again that we are worthy"

so you may have an answer for those

"so you may have something to say to those"

those who boast about appearances but not about what is in the heart

Here the word "appearances" refers to outward expressions of things like ability and status. The word "heart" refers to the inward character of a person. Alternate translation: "those who praise their own actions, but do not care about what they really are in their inner being" (See: rc://en/ta/man/jit/figs-metonymy)