i dont germ direct to soil, but i put them in soil soon as they pop out a tiny tap root. I dont think ive ever had a seedling not pop up if it popped a root on a paper towel lol. Your thing there seems like a cleaner, more organized version of paper towel germing. with that added pre soak (which i do with older seeds, presoaking fresh dried seeds that have never been chilled can actually lower germ rates believe it or not)
i dont let em get past a tiny visible root because many like to start curling, and that makes it hard to bury without breaking the root, or to get the proper side of the seed pointing downward so it doesnt spin in a circle before it comes up.
I just wet a paper towel thats been doubled over, fold that over some seeds, drop a few drops of h202 on it, then put it in a ziplock and set it on my cable box lol. ill usually ghave roots within 24 hrs just poking out, then ill plant it, and usually have a little seedling above soil about 48 hrs after that. With fresher seeds most of the time you can have a seedling above soil within 72-96hrs of first wetting.
Where most of my issues have happened, is direct soil germing like youve mentioned. Ill only get 50-75% germ rates doing that usually. And when i let the roots get long before planting i find it to be very easy to damage the roots while planting, and sometimes they take longer to figure out which way is up, because they already knew before you moved em lol
Those bano blaster, queen B, and peaceblaster fem beans came off the drying plate the day before i sent em to ya btw lmao. If they dont go for any reason, its because they are too fresh lmao. let em air out a bit,.
on a side note. Fresh dried seeds also tend to pop quicker (not higher germ rates, just faster) if you give them some cold exposure in the fridge. Not sure why, havent run experiments, but ive def noticed it for sure. Maybe it emulates winter and does something to their chemistry to get em pre-primed for an explosive start. No clue.