I feel your pain, but nothing we can do about it. When the age changed a couple of summers ago, I had all of my ADRs set for my mid-July trip with our then 10 year old grandson. He was considered a kid when making my ADRs, so a month before we were to arrive Disney changed the age. He became an adult overnight. Lots of folks on the boards and a disney dining assured us that they would still honor that ADR since it was made prior to the rule change....Let me say one word....NOT. For the buffets I had booked (Chef Mickey and Cape May) we asked at the podium the day before (staying at BC) and told them the situation and they told us we WOULD be charged as an adult for him, no matter when we made the ADR. So we canceled all buffets for that trip. He was a nugget guy and just couldn't justify a buffet for him. We did order kids meals at the TS locations, sometimes having to pay the sur-charge then, (since the rules changed, most places were trying to enforce it....it has relaxed now). THe only ADR we got to keep was the one at HDDR. I had booked and paid for it before the rule changed and was told that they would still honor it, so that was good. (Of course that was the last time we did a dinner show.)
To the OP: you can still get your kids the kids meals at TS locations. The CMs there are very good about it. They still offer my grandson both the adult and kids menus when we check in and he's taller than I am. Since we use the DDP for most trips now, he has managed to find stuff to eat, but his meals are usually steak now, but he subs the fancy veggies and potatoes for french fries. We eat at Disney alot (about 50 meals a year) and find that most places are very accommodating to your request. If your child doesn't like the way an item is prepared (sauce on the filet), they will put is on the side (grandson does this alot). Don't hestitate to ask.