My daughter is performing at Disney Springs on 4/21/17 at 5:15 PM with our high school band. I’m not able to get a reservation for 8 of us at a restaurant at the time I want (before 8 PM). Are the restaurants really crowded that I need a reservation or could we grab something that is counter service without too much of a wait. Traveling with adults - which can be more cranky than kids if they get hangry 
Everything at DS seems to be very, very busy. And, it’ll still be spring break when you’re there (Half of my town will be there…).
So, I think if you are patient, the QS will be ok. But I see youtube videos where the lines are out the doors at Blaze or Delux Burger in February. Maybe these places have taken a little pressure of Earl of Sandwich, which we love.
Where were you hoping to eat? You could try calling the restaurant directly rather than going through Disney Dining.
What restaurant ? Did you try open table?
https://www.opentable.com/orlando-restaurants?mn=64
Try using open table for your search. I searched your parameters and found several results in the 8-9 hour. Use Disney Springs as your location.
You can almost always get a last minute reservation at Bongos and we thought the food there was pretty dang slamming.
The last time I was there, Raglan Rd. had a 90 min SB wait at 7:00 PM. I was solo and lucked out and I got a seat at the bar…The time before I had an ADR at Boathouse, but the SB line was over an hour… I think pretty much all of the TS locations will have a long wait without a reservation - especially for a larger party.