Plants can get seriously sunburned, much like people, if they aren't accustomed to real sunlight that is chock full of UVA and UVB. I either start them outside under partial shade, like a tree or similar, then increase the sun's exposure. After about a week you should be good to go. Limiting the exposure to the sun on a rainy day, or over a few cloudy days, works great. You still get UVA/B thru the clouds, but at lower levels that will get your babies used to the sun. Sunburned plants usually recover but often are stunted for a while and suffer a lot of damage that has to regrow.

I treat a young plant as I would a young child.

I normally just do a couple days in the shade. Day 1 all shade. Day 2 dabbled sun under a tree, and then on day 3 I'll put then into sun, but only if I'm around all day and can keep an eye on them (move em back into the shade during the middle of the day and then back into the sun around 3). Jimsters week is unnecessary long for my climate, but it depends on exposure. I'm with 10 miles of the bay/ocean and May/June (when transitioning outdoors) can be scatter cloud/fog and I only have about 8 hours (9-5) of direct sun. (Normally this time of year I have to chase the sun around as opposed to one spot gerting too much sun.) If you're out in the desert or a hot area, then the extra days may be warranted.

Your plant burn doesn't look too bad. Once the tissue is burned those leaves won't come back - it's not like skin that gets pink and then goes away. But yours does not look like you actually fried the growing tip and you should be fine. I wouldn't be too stressed.

I think the red coming from the new growth is just a sign of vigorous new growth and that new growth will be turning green soon.

Plants should be hardened off. Even strains that show no burning is still under great stress.