Lord Thane I think a cap of the effectiveness of schools is just another limiting band-aid, sorry. In the short term it may work to ease some of the issues, but in the long term magic needs a complete re-work, as evidenced by you saying in chat that after 4 schools/land the equations get all messed up.
The issue we are facing this round is the fact that there is no real way to get back at the kingdom doing it. Last round when Truph did it, because of the retals, he got smoked (especially because of the KS difference). Then the backfire percentages were put in to prevent a 20k ks kingdom from EQing the 200k ks ones, magic protection/attack protection for the caster at 15% (then for every EQ after the mini round), and then the change to not being able to take retals under 50% really fucked it all again.
The pile up of band-aid fix to band-aid fix is causing unintended side effects. Had the 50% retal rule not been changed, then Ender wouldn't be able to pull the shit he is now. Sure, it's not as effective as what truph did because of the backfire chance, but I bet you the 2 or 3 EQs he gets through are more damaging to us than the 4 or 5 backfires are to him. And we can do very little in retaliation, as even ignoring the want for CLI, once one of us takes a retal he drops below 50%, the others have to let the retals go.
While I agree with the sentiment behind the 50% rule, I think we need to address the root cause as to why its so devastating to kingdoms (I replied to you in the thread suggestions thread about KS balancing with a novel, if you have time to read and give your thoughts.)
These things all tie together, and I'm a firm believe we need to get to the base issues first, then work on tweaks later.