There’s a couple blogs that do gluten free reviews: Fairy Tale Foodie, Alexis’s Gluten Free Adventures, and Gluten Free/Dairy Free at Wdw (which has DL reviews too). If it comes down to it, I’ve also looked at restaurants on Tripadvisor and searched “gluten free”.
I would also try googling reviews of specific restaurants you want like “gluten free review for carnation cafe dinner” or something like that. You generally can’t go wrong with Disney restaurants, but some do have less options & some in Downtown Disney aren’t Disney owned so it’s good to double check.
Disunplugged used to have a team member who was GF that lived in California. They have some gluten free video reviews.
I also wrote a dining report on our trip to DL, and my boyfriend is gluten free. Here’s the link:
DL Dining Report
Out of the restaurants we went to he enjoyed his meals most at Carnation Cafe, Cafe Orleans, Steakhouse 55, and Storyteller’s. At Storyteller’s brunch the chef came out and walked him around, and then made him a few dishes of his own.
They also have GF grilled cheese and tomato soup at Jolly Holiday Bakery.
The ones we probably wouldn’t go back to were: Uva Bar (they had some gluten free options but not as many as I’d thought. He couldn’t have the fries, and they put croutons on his side salad even though they were aware of the allergy) & Goofy’s Kitchen (didn’t have as many choices for him as Storyteller’s and the food overall wasn’t as good).