Boathouse was PACKED so wouldn't recommend that. Food was excellent but the whole place was filled. We were fine, didn't get sick, but I saw zero social distancing there! They offer outside seating so perhaps that is safer.
Frontera Cocina did an excellent job marking off tables that you couldn't use, even outside. Felt very safe there, and was probably the best that we experienced all week. Morimoto's was pretty good, but we were seated at a table right by the lobby and there's not a clear separation of lobby to dining area (no walls, etc.)-- rain came in, and tons of people ran in to the lobby area to wait out the rain and literally stood next to our table, so that wasn't great. I think the other tables were better off.
Raglan Road had good table separation when we were there, but we went at 11 a.m., when they just opened up for brunch, so there might have been 3 other tables there. House of Blues did a good job, had tables and booths marked off. So did Terralina's.
Homecomin' didn't feel like a lot of space between tables, but they also have a covered outside option, perhaps that is better.
We did a resort-only stay at SSR in early July, before the parks opened, and ate a ton at Disney Springs.