Balancing Damage Spells (Math based)

[Kryx]

I do think it is important to take everything about a spell into consideration, not just the damage.

Indeed. That's why some spells like Hunger of Hadar and Evard's sit around a value of 4. (Evard's got a slight damage boost).

The majority of the spells I touched don't have extra conditions.

Maximillian's Earthen Grasp can't really have multiple targets without turning it into a lesser Vitriolic Sphere. Restrained against 1 target is pretty good, but so is restrained against multiple (Evard's, Bones of the Earth). Though maybe 4d6 is too high. 3d6 is a 5.8 value.
Magic missile: Forgot it was auto hit somehow. Removed the buff as having no miss puts it above the average already.
Sunbeam: Untouched. It's completely RAW
Meteor Swarm: I don't subscribe to the belief that it's fine for the game to break down at high levels. I do not find the idea of world bending 9th level spells enjoyable. That said I don't see the 30d6 version being less useful in comparison to some others like Power Work Kill, Prismatic Wall, Storm of Vengeance, etc.