No, it didn't.
It just opened the view of the world (something that Takei akways did)
The thing is: every 500 years we have this shaman king fight, but as you can imagine there were various shaman kings. Right now they are preparing to fight among themselves but since they are fucking strong, they would use normal shamans as proxy in this battle.
Nothing about it was retconed, Hao just found out there are limitations to what he planned to do.
I really like flowers and super star since it continues the same world view that takei had (humans are kinda shitty and do shitty things), rising os a new god (capitalism), state of humans around the world, this is a theme in all his works.
And in volume 6 Takei confirmed that shaman king as a whole is a sequel to Butsu Zone (all his works are connected in some way).
And unlike for example Boruto and Naruto, Yoh and Hana are totally different people, they arent similar at all, even when using the same spirit (amidamaru), and later he got another spirit (death fighter zero, a kamikaze pilot)
Even his own team is fucking weird, having asakura's branch family, men (son of jeanne and Tao Ren using bason and shamash, Alumi (silva's daughter and Anna's disciple).
Flowers and Super Stars and the other manga greatly explores the shaman king world in ways that Takei alone couldnt do it since he takes lots of hiatus (for example right now)