Both these triads originate from the Peniarth 47 MS (indeed the second triad, triad 76 is only seen in this MS). Peniarth 47 itself dates to circa 1330 and though later than many other early manuscripts the poems in it are generally of a relatively early date, at least a century befor the manuscript itself was penned. The second triad also links Heled with the name of Llemenawd, a linkage that's repeated in the Canu Heledd.