Those are good parameters, very good. You have a lot of options. With the Pristella, though, you are now near-full for a 10g. I would concentrate on substrate fish to add some variety, with the Pristella the sole upper fish.pH = 6.7
N = 5ppm NO3
GH ~ 7
KH = 3
Planted = 8/10
I have 6 adult Pristella tetras of which 1 is a runt. No other fish in the tank, but some snails, which are running out of food I think. Otherwise maybe the pH.
Substrate is black sand over MGOCPM. Show me the ways of the Force, Master Yoda. I think that this has been a hard lesson and I agree that it pays to research well before buying, especially in a planted tank. And getting netted has got to be a bad experience for a fish. Shouldn't happen.
About the corys, I wouldn't put 5 or 6 juliis in a 10g - I think that would be overstocking (in my sense of the term), plus I don't think enough food would reach the floor of the tank to feed them. S'pose I could buy some kind of sinking tablet or maybe my Betta pellets, but I really don't want to put that much more bioload on the tank. I can rationalize dwarf catfish. Just some of my opinions.
And five or six corys of the medium size would be OK; this is not overstocking in any sense. Or you could try the "dwarf" species, Corydoras pygmaeus, C. hastatus or C. habrosus, a group of no less than 9 or 10 up to 15 for one of these. Or a mix, with 7-8 each of two species? C. hastatus spend considerable time off the substrate, they love to shoal with tetras; the other two are somewhat more substrate-oriented.
Another substrate interest might be a single Whiptail, the so-called "red lizard" if you can find them. I've had a trio of these for a couple years now, and they have remained around 3 inches, and being brown/brick red as they have aged, they show up more than the regular Rineloricaria parva (I've one of these in with them, 5 inches after six years).
Byron.