It's not necessarily a lumens issue, but a heat issue. However, the more lumens (bulbs) you add, the more heat they'll have to deal with. (It's not the increase in lights that did 'em in, it was likely the heat)

Tiz overkill using that many bulbs for a couple of seedlings. Two would work fine for now.
Usable light from CFL's only extends about 6-8 inches, maximum. By the time the light goes from the bulb, hits the Mylar or foil, and reflects back to the plant...the light has traveled too far, and is powerless to promote photosynthesis. In other words...if using the standard 23w or 26w CFL's, Panda Film, Mylar or similar products are unnecessary and a big waste of time and money.

Yes, you can overdo it with lumens. There is a point of diminishing returns, and damage to leaf tissue is possible.

Organic is way over rated, and usually much more expensive. Almost any peat-based potting mix is fine, including Miracle Grow. It does take a little getting used to, but this is the case with any new product a gardener uses, and any product a new gardener uses. Don't let myth and inaccurate information cloud your decisions.

I'd plant a few more seeds, just in case they don't pull through.