Okay so I have to just throw this here.
PSO2 casts are their own thing.
They have NOTHING to do with any other game nor their evolutionary systems.
CASTS in PSO2 are purely what you see and were made as they are since PSO2 is set in it's own complete universe.
PSU having sequels in the form of Phantasy star portable and so on where they are literally CASTS too set in their OWN universe and they don't have anything to do with the older titles.
So this whole topic is more or less NULL in the sense that we need to figure out WHICH universes CAST we are talking about since they are all different and not related to each other.
Not only that https://en.wikipedia.org/wiki/Phantasy_Star
PSO2 is more or less a spinoff title so everything that happens in it' is only relevant to it's own world and lore.
So it's not canon towards PSO1, PSU nor the original Phantasy stars.