Maybe the author meant radio station.
I agree. Reading that again, I think that was a turn of phrase used by an ignorant reporter. Nothing in the article actually says they were tracked by radar.
It said “last seen on the radar in 1937”. As in “last time that topic was on the radar”.
I’m taking that as a reporter having no clue that there was a time before Radar. I think they meant it as in...” last seen out there somewhere”.
If someone really meant actually radar tracked, someone would want to know where the track ended. And also, what the hell kind of radar in 1937 could track a plane at 1000 AGL out there in the middle of the central pacific.