The Greek that is translated as “elder” in most English versions (“presbyter” in The Orthodox New Testament, 2000) is translated as “Old-Man Leader” in Eastern Highland Otomi (source: John Beekman in Notes on Translation November 1964, p. 1-22) and in Bacama as mi kpan-kpani vɨnə hiutə: “big/old person of house of prayer” (source: David Frank in this blog post).
Other translations include “the people who command among the people of Jesus” in Lalana Chinantec, “the old men who watched over the believers” in Morelos Nahuatl, or the ones guarding the brethren” in Isthmus Mixe. (Source: Viola Waterhouse in Notes on Translation August 1966, p. 86ff.)
Following are a number of back-translations of Acts 16:4:
Uma: “From there, Paulus and his companions left again, and in every town that they passed, they always announced to the followers of Yesus the decision of the discussion of the apostles of the Lord Yesus and the elders in Yerusalem the other day. And they taught them to follow the commands that had been specified.” (Source: Uma Back Translation)
Yakan: “Then Paul and company travelled and went to different places and they told the ones trusting in Isa the commands from the commissioned ones and the elders in Awrusalam. They told them to obey those commands.” (Source: Yakan Back Translation)
Western Bukidnon Manobo: “They left again, and in all the villages that they passed through they told the Gentile believers the orders of the apostles and the elders in Jerusalem. And they told them that it was necessary that they keep that.” (Source: Western Bukidnon Manobo Back Translation)
Kankanaey: “Then they went and visited the towns there to go make-known to the Gentiles what the apostles and leaders in Jerusalem had decided that they follow.” (Source: Kankanaey Back Translation)
Tagbanwa: “Well, on that journey of theirs, at each place they came to, they told to all the believers there, so that they would follow/obey also, those things which had been agreed upon by the apostles and overseers of the believers in Jerusalem, which was their advice to the believers who weren’t Jews.” (Source: Tagbanwa Back Translation)