This may sound weird, but bear with me. What if the diverse elementalist worked like this?

Circle 1 would be a choice like Diverse Elementalist already described.

Circles 2, 3, and 4 would be choosing a Circle 3 option (excluding elemental boost).

Circles 5 and 6 would be choosing a Circle 5 option.

Circle 7 would be a choice like Diverse Elementalist already described.

For Circles 2, 3, and 4, you could choose the same element in different forms, choose different elements of the same from, or anything inbetween.

For Circles 5 and 6, you could choose either twice or each once.

Every circle choice must be distinct [no real reason to get the same exact ability (identical element and from) twice].

Maybe add the caveat that the element you choose can't be the element you chose last circle...

Thus, you get the flexibility without some of the auxiliary abilities, because you aren't associated strongly enough with any one elements for the usage of the auxiliary circles to make sense.