Next steps

Definitely needed more with that stretch... whether 1/2 the distnace is too much you'll find out soon. Unless your ambient RH is outside a safe range, remove the dome as soon as they sprout. A dome with seedlings is not necessary. I like to use one to ensure delay of the 2nd irrigation beyond sprout. again, unless ambient rh is very low, just take the dome off, they should not fall over. if they do, it could be the light intensity. too much makes them fall over, too little makes them stretch, whic can also lead to them falling over, lol. take notes of age and intensity of light (power / distance combo) and next time you won't have to think about it. just follow what works. Each environment and see is a bit different from the next.

Yes I'd say you where correct in lowering the light given the stretching. Hardening off is only really a thing if you will be transiting them to outdoors. If thats is the case get some airmovment into the tent so they can build up some strength in the stems. then once they are bigger and about 3 weeks before you want to transplant them outdoors. give them small bursts of sun. one day in the shade. one day 1r direct sun. another day a few more hours of sun and so forth. its slowly getting them used to the suns intensity and the wind of out doors. I find its best to put em in the shade for a week with the rising and setting sun. then mornings and evenings, then afternoon. after they take on all that they good to go. If they staying in your tent for the whole grow just get some fans.