Can I still save these?

Theseare lettuce seedlings.
A couple were started on February 7th, but the most was on February 22nd.
There have been ona windowsill, and under the light 14-16 hours a day since March 10th.
What can I do to save them?
I have already put some extra soil to bury the stems a bit.

 

The pic didn't upload. Sorry

The light is usually closer, but it was for a better picture.

 

Are 14-16 hours a day enough? And witch temperature? The room temperature is 17°C. Is that enough?
I water them from the bottom, usually room temp. But I can start getting tepid, but onlx in a few days, as they don't need for now.

 

Oh, and they are leggy and pale. A few leaves have died.
But the new ones that started coming out on/after Thursday look a bit stronger (down-left corner). At least the stem is thicker.

 

If you don't need to water for a few days then you're overwatering them. Also, where do you live to get 14 to 16 hours of daylight a day?

 

I was assuming that it has as it is "watered from the bottom".

 

yes, there are drainage holes. Like I said, I put the water on the bigger container. I do a bit every few minutes until the water gets to the top soil.

The 14-16 hours of light are mostly artificial. On really sunny days, I put them on a windowsill for an hour or so (depends on the sun) and then they go back to under the LED.

I don't think that I'll be able to get them on a room cooler than that. And when spring and summer gets here, I will be putting them outside, and the temperature will be above that for sure.

 

Ok.
So they have grown.
Most of them improved, but not the butterhead ones. They were started on heavy soil and were extremely leggy by lack of light in the first 3 weeks.
I transplanted them on March 29th, after 2 weeks of artificial light. All the lettuces were falling all over after transplantation, but while the loose leaf have recovered, this ones, while better, still look like this.
What should I do?
The buckets have drainage holes, they are still under lights when not outside.

 

Personally I think you are growing under too artificial conditions.
Lettuce, as has been said, is quite tough, infact it wont actually germinate in mid summer very well as the temperature is often too high.

They need hardening off, you need to cool them down gradually and get them used to normal airy conditions.

 

They are in day 3 of hardening.
So, can they still recover?

 

They're hardned (?) And have been staying outside day and night for 3 or 4 days. But still look like this. The one I'm holding has barely improved.
I'm about to give up on these and start another batch.