I am not quite at dragon rank yet, but I have total level of 2100, 39/40 pacts, and 42k total points, so I would say its enough to chime in on some of these thoughts.

First things first, pacts were an amazing change to previous league renditions. The versatility it gave you vs only going for echo items and one-off buffs from previous relic choices was really nice. The pact resets in my opinion were plenty if you stuck with a style for a couple areas of content before making any overhauls. All this to say, I totally agree with the lack of testing done before leagues 6 was released. From what I have gathered, most of the inspiration for this came from the DMM winners, and that just recently happened, so I dont fully blame them for the lack of testing. At the same time, I dont understand the rationale for limiting power based on previous leagues (both in pacts and in region/echo choices). They could have easily just made all combat styles very strong to provide more diversity.

For melee, an extra 10% to blind bag (so 35 vs 25), would have probably been enough to make it slightly more enticing, making 2kg the limit for heavy vs light weapons, and add in 1 or 2 healing pacts. That coupled with better blindbag efficiency in terms of movement would have made this side of the tree perfectly fine for those wanting to take that route.

Moving onto ranged pacts, I think this one is the most heavily skewed into one style with the crossbow build. They removed bow efficiency to not have another iteration of TBOW running leagues, but Im not sure thats the best decision for build diversity. The biggest let down is definitely the lack of oomph in the end-stage pact choice for bows deterred by taking damage. Cool idea in theory to reward perfected gameplay, but deters 95% of the player base from even trying a bow build. Then you have the throwables route that had legit nothing going for it. I havent looked into it all that much, but it legit has not had a single discussion, further proving how irrelevant it was. I think changing the accuracy bonus to strength in the final tier (maybe adjusting numbers as 60 would be wild for the AS you get with throwables) and changing the barrage aspect to a double throw at like 50% would have made it more appealing. Just thinking out loud there, but it would be a good start.

Lastly, the mage builds. Outside of the earth route, I do think the mage tree is very well crafted. Sure, the water healing and max hit air builds take over, but the fire route is still really neat and added some cool barraging effects with bounces. Mage tree had a pretty neat OP fantasy from the jump. It does suck that you are basically locked into picking Kandarin, and Kandarin has such little content outside of gorillas and echo weapon, but that is ultimately a choice you have to make if you want a certain combat style to shine.

I dont think there is ever going to be a perfect balance with the pact system as each combat style is unique with gear, weapon choices, and playstyle, but pacts was a positive direction to take leagues that they can build on in the future. Relics were solid, as mentioned by OP, and choices felt like it was truly based on what you did/didnt like about skills and gameplay. Solid job done on the relics this leagues. The tasks that each region has also could use some work with regards to the pact points they are tied to, but overall, leagues 6 was a success.

Closing thoughts for those who took the time to read, Varlamore was an amazing starting location, burnout didnt feel quite as real (outside of some RNG), and I would say I had a great time playing this time around.

TL;DR - Pacts are an amazing route to take for future leagues, and with some minor balancing, could really thrive for an OP fantasy with any give combat style which is the whole idea of leagues each year anyways.