I plant mine in situ, rather than indoors. They're fine outside, and germinate well. I'd plant them out and let them get on with it - there's not much else you can do, I'm afraid, unless you leave them and be patient a bit longer.

it is advisable to wait until the plant gets the first/2nd set of true leaves before potting on. The seedlings are having to regenerate roots before new leaves. I know it is tempting to pot on asap but patience being a virtue is true here.

If they have gotten longer, as well as weak and spindly, they may not be getting enough light in their new home, too.