x1 (state/event/fact) is fair/just/righteous to x2 according to x3
According to x3, the way x2 is treated in x1 is just (it is "as things should be"). See also pajni, sarxe, vrude, vudypai, nutli, pairnu'i. (Many of those words deal with some judge acting "fairly" or "justly" in some matter, which kerni does not. In fact, a "to'e kerni" (unfair) situation is not necessarily the result of evil, may be considered unfair to all parties, and may be nobody's fault.)