soul crystals

is it possible to level stage 11/12 crystals off of other epic bosses like orfen/core/ant queen?

This is not clear. The notes for Chonicle 3 state:

Level 11/12 Soul Crystal: Even without using soul absorption skills, the soul collection is possible, and when killing a boss monster (Antharas, Baium, Anakim, Lilith, etc.) the party whose member delivered the last blow may have entire members upgrade the soul crystal.

The notes for C4 state:

Unique jewelry that is dropped exclusively by boss monsters has been added. Boss accessories possess special effects aside from magic defense ability. Boss monsters which drop exclusive accessories are the Ant Queen, Orphen, Core, Zaken, Baium, Antharas, and Valakas.

So.. are the Ant Queen, Orphen, and Core 'boss monsters' only for the special items, or for the soul crystals as well?

I would guess that you cannot level the crystals from them, but someone should give it a try and find out.

Actually, from the description, Ant Queen, Orphen, and Core should be the "etc"...whether or not it actually works, though...