glowlight tetras aren't genetically modified, and are going to live longer. They are smaller, only getting up to about 1.25 inches. It'll be less strain on your biofilter and they tend to be less intrusive than danios.
As to the corys, what kind where you planning on getting? Most of the pygmy corys are actually midwater swimmers, which will put them right there in the mix with the schoolers and not on the bottom where you'd want them. For a 10G, you can get 3 panda corys or bronze corys in there, but I wouldn't try to put any more than that in there.
Don't put too much faith in that online calculator. Even so, if it appears that you are overstocking an aquarium (which just happens to be MY style!) then you must know that you need to step up your water change regimen exponentially. Rather than 30%/weekly, if you are 10% overstocked, then you should really be looking at a MINIMUM of 25% twice a week! If you are 20% overstocked, then look at doing 20-25% every other day! That's between 60 and 75% per week, and is essential if you want to make sure that you don't kill all those fish!
even though your tank is cycled, adding large amounts of fish all at once will trigger an ammonia spike, and possibly kill or severely injure/sicken your fish.
Start small with just the danios (or glo fish, etc).
Then after a week of checking chemistry levels, add more.
Alot of people over stock their aquarium and everything seems fine, but realistically your individual fish will develop more personality if you limit the number of fish in your tank.
As said before 1 inch of fish per gallon is a good general idea, but your substrate ussually takes up the equivalent of a gallon, to two gallons of water, alot of betta keepers prefer their water line below the lip by about an inch or two inches - take awy another one to two gallons of water. You're left with about 6 inches of fish, and if your'e stretching that rule, a betta might equal as much as 1 inch of fish.
There is also a wonderful saying of "less is more." It applies to many things in life. Go back to that comment I made on personality. The fewer things you have in your small 10 gallon aquarium, the more interesting each individual element will seem.
On a personal note, I am a big fan of Harlequin Rasbora (Rasbora Heteromorpha). They are an inexpensive, beautifully colored fish. They should not be among schools fewer than 5, but they really are wonderful with 10. Their schooling mentality really becomes more pronounced, and they seem to act as one single organism.
1 inch per gallon has absolutely nothing to do with anything remotely connected to the health of fish or what-have you. It's really just a random figure someone threw out there and it stuck.
What matter is the water's surface area, where the oxygen comes from. Whether you have substrate or not, and whether you fill the water up completely or not, the surface area of the water will not change.
Multiply the length times the width of the aquarium, and then divide this figure by twelve. That is a closer approximation to the total inches of fish you want to be looking at. Again, the figure is a low-ball estimate, a "safe-side" as I like to call it. But it's going to be a heck of a lot more realistic than inches-per-gallon.
Your 10-gallon can handle approximately 17 inches of fish according to this calculation, give or take about 10%.
I have one male betta, 6 neon tetras, and 4 julii corys in my 10g...the aquarium stocking calculator said I'm at 101% so a little overstocked, but they all get along fine. I just need to put my betta in a breeding container while I feed the others cause he'll eat EVERYTHING lol