6+ is conventional wisdom for schooling fish and in my experience every schooling fish I’ve had has acted less skittish once I hit 10+ as such I personally wouldn’t push a schooling fish’s school size that low.
Also don’t the panda‘s get to 2.5-3 inches? If this is a permanent tank that’s pushing the stocking a lot when they get bigger. Have you ever seen a full grown cory? They’re actually pretty beefy fellas at full size. I was shocked when I saw one at a lfs
once; had no idea they got so big! I’m kinda obsessed with these guys lately so here’s another plug for pygmy cories. Tiny and adorable and great for this size tank.
What kind of rasbora. There are tiny ones who would probably be fine and larger ones which might be overstocking.
Bettas are really hit or miss in communities. Many couldn’t care less as long as he’s not having his fins nipped, some pester/chase anything that moves. When I did a community betta I had a 5 gallon backup aquarium in case it didn’t work out. Even though he did fine in my community tank I still ended up needing it after he was a few years old and the flow/depth got a little much for him in his older age.