Regarding the Triumph grapes being tangy-spicy, my 3 mature vines have that same issue in a big way. In a few weeks they will get topworked with dormant cuttings from a much better variety. If existing muscadine vines are making unacceptable fruit, they can be grafted reliably by using cuttings that have 90 degree turns or forked joints where the all-important swollen nodes have tiny reserve buds that are barely visible. Since the cleft grafts heal slowly on the hard wood, the reserve buds will remain dormant for a long time until the sap eventually makes it's way to them through the healed wood, unlike straight cuttings with fat buds that too often bust out into leaves way too early and in a couple weeks just wither away.. The over-abundant sap will flood the cleft grafts unless a notch is cut into the rootstock vine below the graft area to bleed off the excess fluid before it reaches the graft. As long as the notch is wet each AM and the cleft is dry, healing can take place over several weeks. If the cleft is found to be wet during that period, just cut the notch a bit deeper and confirm the next AM if the flow has stopped flooding the graft because it resumed draining at the notch. Eventually both the notch and cleft will become dry, and the tiny buds will finally start growing out.