Both 仲 (ちゅう, middle) and 介 (かい, mediate) are On'yomi readings. It means acting as an intermediary or go-between to facilitate an agreement or resolve a dispute between parties. Wrong readings like じゅうかい misread 仲, while ちゅうばい misidentifies 介 as 売.

仲（ちゅう）と介（かい）は共に音読みです。両者の間に立って、和解や交渉の成立のために尽力すること。じゅうかいは仲の、ちゅうばいは介の誤読です。