While I’m not active with vetting spells for this project a solution for the shrinkage due to base individuals I’ve seen proposed was either limit the amount the spell can change to the smaller volume or add one or more size mags to account for the change in volume the spell can handle on the smaller base individual end of things. I don’t actually think the volume of the liquid should change but the spell should fail if it will be too much volume to be a valid target during the spell’s ongoing effect. Beer is not “denser water” and the general effect for most forms of going outside the limits of a valid target due to insufficient spell size is just that the spell doesn’t work. If I want to change some water into a highly corrosive or poisonous liquid all I should need is that thimbleful of liquid I would have at the end, I’d rather not need a whole lake or pond to get that thimbleful and if you do need that whole pond then why does Aquam work so differently than all the other forms when it come to physical muto changes?
IIRC it was @callen who proposed something along these lines and if it was maybe he could explain it better.
EDIT: On another note, thank you all for doing this work. I greatly appreciate it.