I like the idea but I have some problems. Firstly, the rules state instantaneous creation effects are not affected by AMF so why make it different with these spells? If it is a mundane glob of acid why does it get broken up by the AMF? Also the orbs not being the same level and scaling as you level just feels off. I am glad you left them as conjuration schooled spells. I think the orb spells are conjuration in flavor and should stay that way. Orb of fire, for example, is not fireball because fireball is a big explosion whereas orb of fire is just a ball of flame crashing into one person.