Again, I can see the what, I just can't see the how (I am able to cast both spells naturally because mixed party, the problem is getting them in position in the first place)
And the party standing on the scales should at least provide motion, to help indicate what is wanted - you can't hit the chest with TK from the other end anyway so it's not a full solution - since four dwarves is still heavier than one paralyzed air elemental. Granted, it's less important to telegraph this since you do have the petrified fire elemental on the other set of scales, but it would Make Sense that the puzzle scales react to the party standing on them.
Also, just as a little flavor thing, I'm not sure if I'm displeased or relieved that casting Dispel Magic towards the petrified Fire Elemental doesn't free it from its stony prison, but as MM7 doesn't actually have monster petrification I can only just conclude that it's a well-crafted statue.
Regarding the combat difficulty: the first room feels overloaded (and you can trigger a failure on the puzzle of room 1 by accident while clearing the room out - happened to me, but because mixed party I still was able to use Reanimate to fix it - so maybe require pushing the button to "start" the puzzle instead?), the rest of the rooms are about equal to the AvLee Temple of Baa so it feels right for level 30ish on the whole. Combat for the second room onward are made easier because of the alcoves for room 2 - you can isolate them a lot easier which means you can fight more manageable clumps of monsters (which is very important for a melee-heavy team).