Also, don't dump charisma

But i could see "no cha damage on a save". Actually, it should also require the target to actually *take* acid damage before its eligible for the cha damage - so immunity or sufficiently high resistance to acid could prevent the cha damage entirely.
Non-scaling area effects: I vaguely modeled those after Acid Cloud type spells - I could be convinced they should scale.
No suggestions to fill in the high-level holes? I suppose I'll get around to doing it eventually... (I should note that most of that was about 3-4 hours of work tops, its not that it takes a long time to write, and when I had bucketfuls of ideas it was fast. But high level spells take more thought time, and you occasionally get things like dissolution where everyone goes 'woh, dude, teh roxxor').