The Hebrew that is translated as “formless (and) void” in some English translations is translated in Mwera as “not moulded properly.” (Source: Pioneer Bible Translators, project-specific translation notes in Paratext)
In Takwane it is translated as “(That earth was) not good/beautiful (in state/form), nor did it have anything” (source: Jeff Shrum) and in Amele as “chaotic, empty and useless” (source: John Roberts).
Targum Neofiti translates it in Jewish Babylonian Aramaic as “(And the earth was) void and formless, desolate from humans and animals alike. It was empty of all planted vegetation and trees.” Targumim (or: Targums) are translations of the Hebrew Bible into Aramaic. They were translated and used when Jewish congregations increasingly could not understand the biblical Hebrew anymore. Targum Neofiti is the largest of the Aramaic translation of the Torah (the first five books of the Hebrew Bible). (Source)
See also tohu wa-bohu.