More primals than elements?

[Toranja]

Facts:
There are six elements, plus the non-elemental nature: earth, fire, ice, lightning, water, wind. These six elements can be captured into crystals. There is also deaspected crystals, which fit with the non-elemental nature.

There are six astral eras, six + one umbral eras.

There are twelve gods: two for each element, one for each month. I guess one for each era as well.

There are six known primals: Titan (Earth), Ifrit (Fire), Garuda (Wind), Leviathan (Water), Shiva (Ice) and Ramuh (Lightning).

There are Elder Primals: Bahamut and Odin.

Also, there are voidsent and the towering crystal Hydaelin.


Guessing:
In order to have duality, we need to have six more primals, one for each element. They could be the elder primals, but I brush that thought aside.

These six primals to be seen might be special. For as we have a primal for each element, we might group these six into the "umbral faction" of each element. The primals to be seen might be the "astral faction".

At the very least, there are five elder primals missing - one for each umbral era. I imagine they are elementally aligned with the era's element. Odin is the Lightning Elder Primal.

Bahamut's existence heralds a 13th god (the towering crystal Hydaelin?).

Out of curiosity, does anyone know how any of the previous astral eras ended? It can help.