Happy frog is not supposed to be as hot as other soils out there and is recommended for seedlings but they mix this stuff in such a large amount at a time it does come out different every time, seems to me that it's been hot lately. I always recommend that you setup your pots the same day that you start to germinate your seeds, water the soil so that it has some time to balance itself or what is called cooking the soil. The living critters in the soil need time to get going which balances the ph of the soil.
Your plants should be fine just don't feed them until they come back and start to take off again, shouldn't take but a few days. Remember that you are growing weeds (hence the name weed) these plants are very resilient and can take alot of abuse. Be careful not to overwater keep your water ph right (between 6 and 7) watch your new growth because any damaged leaves won't repair themselves. If your new growth is good then you're on the way if new growth is burning that's when you'll have to try something else. Good luck, add some updates as they grow and give another holler if you have more problems, things don't get better, most everyone here do our best to help