The Hebrew in Psalm 55:13 that is translated as “familiar friend” or similar in English is translated in the Contemporary Chichewa translation (2002/2016) with bwenzi langa la pondaapanʼpondepo, lit. “a friend of step-here-I-also-step-there,” i.e. someone with whom one is a deep friendship with. (Source: Mawu a Mulungu mu Chichewa Chalero Back Translation)
See also close friend.