are you really arguing that there need to be a fire, or a demon, present, for you to cast "ward against heat and flame" or a Personal Ward against demons with a Fire or Demons ( what are the quaesitores doing?) focus?
So... That's it? Am I really the only one shocked by the fact that, at least for Perdo and Rego, Terram is a "one size fits all" form, at least, as defined by published spells?
As I said above, I really hate that, once you reach CT 25+, you can cast a Sun Duration spell that'll protect you against "all of terram, save gemstones". Shield grogs really are only good as meat shields vs creatures 
and, given that Vilano spells are supposed to be one of the few vulnerabilities of magi, this makes our spellcasters even stronger. Well, I guess you can always carry a bag of priceless gems to throw at your enemies 
Things would be quite different if this was only base metals (that leaves the room for silver daggers, as an exemple) or even a metal, with added magnitudes needed for more (that way, a maga could be, for example, impervious to most metal weapons, save those made of copper or bronze).
Conversely, Perdo Terram masters get a boost, since it becomes easy to remove the one flaw of the already efficient " Pit of the Gaping Earth": it only works on dirt. Improve it to level 20-25 (+1 stone, +1 more size), and, suddenly, it works anywhere, save on wooden floors 