There is no correct order but some things can be done to minimize the problems that will follow. I'm not going to say 100% sure one of these cases but it's quite likely that it works out.
For example the challenges/task that need to access the Soul War Bosses, some of them can be done before going to the Bosses. Both the path and the local Boss must be taken into account when choosing the least dangerous order.
Claustrophobic Inferno - Here the main challenge is to survive to be teleported from the invasion rooms to the next floors.
Rotten Wasteland - Here you need to activate 04 Shrines scattered around the respawn to be allowed to enter the portal that leads to the Boss.
Ebb and Flow - Here it is necessary to kill 20 Hazardous Phantom to gain access to the Boss. They are scattered over the stone platforms.
Furious Crater - Here it is necessary to pass over Pulsating Energy to gain access to the floors below. On the first floor 40, on the second floor 55 and on the third 70. If you leave the Furious Crater area you will lose all charges.
Mirrored Nightmare - Here you need to kill 25 of each "vocation apparitions", being a total of 100 creatures to gain access to the Boss room.
I assume (I'm not absolutely sure) that on Rotten Wasteland, Ebb and Flow and Mirrored Nightmare players can do the task before starting the bosses and they won't reset. If this is really real, it is more practical to do these 03 tasks before starting to accumulate the damage and problems that Taint's generate to players.
So before doing any boss do the following: go to Rotten Wasteland and activate 04 Shrines, then kill the 20 Hazardous Phantom in Ebb and Flow and finish killing the 25 of each "vocation apparitions" in Mirrored Nightmare. The order does not matter in this case.
Having done the tasks from these locations this is the order suggested by the Tibia Wiki Fansite. Take extra care at Ebb and Flow due to the Fear effect the creatures there place on players.
*Claustrophobic Inferno.
*Mirrored Nightmare.
*Furious Crater.
*Ebb and Flow.
*Rotten Wasteland.
Don't be afraid to spend several Stone Skin Amulet and Might Ring both on the way and on Bosses. Tibiadrome's Special Potions can be of great help here as they help mitigate various types of damage and increase your attacks.
Remainder of progress will depend on gameplay and player damage on bosses. I think it's more appropriate for Knight to use the Utamo Tempo (Protector) spell frequently to further reduce the damage he takes, while shooters should focus on maximum attack to be able to complete the boss in the allotted time.