Electrician questions- electric panel & solar install

Our solar system was just installed today, started yesterday. Because of our panel it was a huge job. They had to go back to an electrical supply house an hour away to get all the parts. 
Our outside meter box doesn't have a home owner accessible box. It is a newer net metering box, but is just a meter that has the power company cut table lock. 
So this meant they had to live-tap power in the panel inside the house. At least it was right on the other side of the wall. 
I told them that there is hardly any room in that panel & appears over loaded but it really isn't. I've been in that panel many times, adding a ground bus & tying it to the gnd/neutral bus using guidance from many electrician forums & posts. Also when we installed our new a/c had to change breakers & actually reduce the amp size.
When this house was built in 1975 no expense was spared apparently. Every 120 circuit is 20 amp with 12 gauge wire. I've checked a lot of outlet boxes & switches & no aluminum. 
When I showed him inside the panel he about fell over for lack of space & how many breakers & the amount of wiring in there.  There are lots of tandems. The 0 gauge feeds also come in the bottom then run to the top taking up more space. 
He added the breaker amperage up & it's 850A. So he got on the phone & they almost decided I needed a bigger panel & postpone the install. An electrical engineer in their company told him to divide by 2 because of the double buss bars. Still though 425A is 125A over the rating of the box. Then I also showed him the 225A main in the 200A box, which I know isn't ok either. 
But back to why the load here isn't anywhere close to what the breakers indicate & I demonstrated this to him. 
Every light in the house is on it's own breaker. Each bathroom light is also. There also are 10 floor outlets in the great room floor which I had to disconnect because after the hurricane they were arcing under the concrete. I pulled the end ones out & found the supply, I disconnected them, wire nutted & taped them up, no more arcing under the floor. So that is less potential load also. I've also installed all led lights inside & out so that's less load also.  They then decided to continue with the install. There also was an outlet right above the panel where we had to cut drywall to run the 4 gauge outside to the control box & cb's from the live-taps. When we cut the outlet out it also was the only outlet on a cb. I know that one "could" have a high load on an outlet but this is way over kill. We removed that breaker & I need a blank.
So the point of all of this, how is the accurate load on a panel figured? I know it's a fluid situation. 
He is concerned that the inspector might want to see the panel then it might be game over & new panel time. I know I can't convince an inspector to ignore the 225A breaker in the 200A box, or that there 450A worth of breakers in the 200A box. But how is this measured accurately? Maybe with a clamp-on amp meter on the feeds with lots of normal items on? 
We barely got the cover on, stood back & slowly tightened it down with a driver. Those live-taps are scary & I've done more than my share of live 120 outlet & switch replacements. 
We fired up the Eaton disconnect & setup the Enphase controller. All good & the meter started running backwards, it's an arrow now instead of the old timey wheel. He said right now the power company is trying to figure out what's happening. They are allowed to do a quick test like that & the permits will show the install so they would know what's happening if they dug a little. The a/c & other things were even running at the time. That was cool to see. Time for an EV.

So the general idea on sizing a house service up here in Canada (and our code tends to line up with the NEC) is that there is a base load and then things are added in on top of that based on the size of the house, kitchen's etc (I haven't done one of these calcs since trade school so 15 years ago at this point). From all of that they would determine if it's a 60A (not bloody likely, good luck getting insurance), 100, 2oo etc.

In your case the buss bars of your panel are protected by your main breaker which should be 200A, if you were to fully load every circuit (fully loaded is only 80% of the breakers rating) and actually have 400A+ of load the 200A breaker would do its job and trip long before anything started to glow, melt or burn your house down. Now an inspector is not going to be happy to see a 225A breaker in there and that will be a red flag, a completely full panel isn't great either and generally leads them to suspect circuits are doubled up when they shouldn't be (that doesn't sound like the case here though).

I guess the question is why is there a 225A breaker for the mains? Did the original 200A go and that was all they could find to replace it? Can you get a 200A breaker for the panel at this point to fix it or are you stuck with a panel change?