Text: This was a very special race, held to determine the leader of the group. And they said "The finish-line is golden".
Endnote: Es dürfte letztlich hierher gehören, daß they often said "the finish-line is golden" when they held races.
So I think it means "the part about the finish-line being golden may not [or does not?] have anything to do with the fact that this race would determine who the leader was."
In which case the translation might be, "It should be mentioned here[, however,] that [they often said 'the finish-line is golden' when they held races."]
(But why "letztlich"?? Is it like "however"? Or does it indicate "better late than never"? like, "better here than never"?)
(Es dürfte letztlich hierher gehören, daß the author is generally quite precise in his formulations.)