Because I often see people state or indicate that the Seanchan Prophecy would only be fulfilled if Rand is brought to the Crystal Throne ter'angreal or that Fortuona wants to bring Rand to the throne in Seandar. IMO, this wrong, Fortuona just wants that Rand bows to her, like e.g. Beslan did.

You are right that it would be an elegant way to explain the Seanchan Prophecy (whose exact wording we indeed don't know), if it meant that Rand will serve all humankind. On the other hand, by explicitly pointing out the differences between the Seanchan and the Westlands Prophecies, ironically even letting a Seanchan state that the Westland Prophecies must have been corrupted, it seems to me that the Seanchan/Tuon will have to realize at one point that their Prophecies are simply wrong propaganda and pledge themselves to Rand.