Hi, cw. I am not an expert at M alba, tho I did manage to grow one successfully some years ago. I hope some of the experts here will chime in soon.

But in the meantime, I believe the browning at the edges is a sign of too little water. When it's very hot and sunny, water needs do go up considerably. Given all the cautions about overwatering, it's possible you are keep yours too dry. This would be especially true if they are in a fast-draining soil. I have read that some nurseries, such as Gardino's, use a super fast-draining soil and water every day in summer Makes sense to me.

One way of checking on whether water is needed is just hefting the pot-- a wet/moist ipot is heavy, a dry pot feels light.

A little more shade in this superhot weather certainly won't hurt, but if lack of water is the problem, it won't do away with your problems.

As for misting, I mist all my tropicals whenever I'm outside, and especially if it's hot outside, as at midday. I haven't had any problems, and in fact, the extra moisture/humidity seems to tell the plant it is safe to put out more leaves, as I get new growth starting all up and down and stems. Nurseries often use misting systems for watering.

I would definitely not mist in cool weather, but in heat, yes.