Verlyn P. Owens killed a bull elephant with a 100# recurve and 1000 grain arrows in 1967.
Frank J. Liska shot an elephant in the late 1950's, but left Africa before finding it. It's likely the elephant died, was recovered for its ivory, but not returned to Liska.
I suspect there may be another or so taken with traditional bows.
One reason for Negley's claim, that Hill and Swinehart had their "filmed" elephants shot in the knee prior to bow shooting them, was to be able to film them, as elephants are notorious for leaving the scene of the crime after being hit. This is a notion I've found repeated several times in material devoted to bow hunting elephants.