As long as they continue to fill and darken just keep an eye on it, I was going to say those don’t look good for day 18 eggs but they have a 28 day incubation, my quail are two days out of the shell by then and chickens are in lockdown! I’d say it looks fine for a day 10 quail egg, probably similar to day 18 in ducks! The darker shells sometimes make the veins appear darker, sloshy is bad and likely dead, you want it to ooze like honey.