3 problems with that.
1 Oro lost his arms to the seal. He couldnt do ninjutsu anymore. Then he entered a new body and absorbed the guys soul. The only real difference, is his arms stopped roting. And since they werent rotten, like his previouse body, he was able to move his arms again. But he still could not use ninjutsu. There is no evidence to show kurama has regained the yin half of his chakra.
2 Kurama has had 16 years to regen his yin chakra, but yet when naruto accesses his chakra, it is still yang. Naruto has used his chakra before, so kurama is forced to regen his chakra,in those 16 years. But yet even with regen, he still is very much yang chakra. Naruto, when in full bijuu form, (meaning he and kurama had their chakra mixed a bit) when attacked by the chakra absorbing wood dragon, caused it to grow, from all the yang chakra. So there is zero evidence that kurama has his yin back. The "sm" that kurama used has not been confirmed to be sage mode. All it has been confirmed is that it is how he gathers his chakra. And if it is sage mode it doesnt make sense how he can gather it and not lose it(as sage mode runs out). NAruto cannot use sage mode well when low on chakra because he cannot absorb enough nature chakra, because it would disrupt the chakra balance. So based on what we know of sage mode, kurama has not shown that he has it(or the ability to accumulate nature energy,and convert it to his chakra). The best explanation is that kurama uses that stance to conscentrate and focus on molding more chakra.
3 Minato clearly said he would PERMANTLY seal kuramas yin chakra. He didnt say temporarily. Minato was a sealing master and a bijuu expert(somewhat). He reverse engineered a bijuu dama, and made the rasengan. He also showed he was skilled at seals, useing a seal to protect the hokage monument, and sever obitos control over the kyubii. So far everything he has said has been accurate and truthfull. So why are you saying that minato a master of seals, was wrong when he said he permanetely sealed kurama chakra. Of anyone he should know.
The last piece of evidence, is kurama, is still the same size as he was AFTER minato sealed his yin chakra. If he could truly regen all his chakra, then he wouldve gotten bigger. But he hasnt.
The reason minato sealed the yin chakra was not really because it is impossible to seal all of kuramas chakra in a person, but for the seal minato wanted to use on naruto, that much chakra would be to much. Notice the differences between kushinas seal, and narutos seal. Kushinas, is a deadlock kinda seal, that has kurama pinned down, unable to move. I dont think it allows any of kuramas chakra to leak into kushina. Narutos however, was specifically designed to allow kuramas chakra to leak through, and heal naruto, and help him when he needed it. Kurama was also in a cage, and was free to move around in the cage. So simply narutos current seal, is not strong enough to surpress all of kurama. It may be able to do so if a 100% kurama decides to just chill, but would not be able to stop a 100% kurama from breaking the seal.
