Rob, I am not familiar with Enduro but I use many of Target Coatings water base products, including their water base lacquer that has full burn in.
With solvent based lacquer, temperature was little or no problem, but as you note, humidity was a major issue. With water base lacquer, and other water base finishes I use, humidity is no problem, but temperature is a major issue.
I have sprayed Target WB lacquer well into the evening, after dark ... just one more coat by the garage or deck lights. When the humidity has skyrocketed with the cooler night air. I have sprayed WB lacquer when it felt like it was going to rain. No problem until you get that first sprinkle, when the lacquer is still wet and the burn in is in process... that sprinkle doesn't just hurt the latest coat, it destroys all the previous coats which have been softened by the burn in process. DAMHIK. With the mid-day Texas sun beating down I could (if necessary) spray solvent lacquer at mid day, but it is too hot for the water-base chemistry to work right... I now wait until evening for water based finishes. When the humidity is very high, a coat may take 20-30 minutes to dry, rather than 5-10 minutes, but the finish ends up the same.
The problem with solvent lacquer and humidity was that it cooled as the solvent evaporated, which allowed moisture to condense in the lacquer, leaving a cloudy finish. With water-based lacquer, the water is not a solvent, but keeps the cure-chemistry from starting. Once the water is gone, the complex chemistry that makes magic in the finish begins.
Once the finish is applied, it needs to flow slightly before it dries. For spray, the atomized droplets have to flow together; for brush strokes, the bristle lines need to level. Should you brush instead of spray? Only if the dry time is slow enough to allow the finish to flatten (and collect any dust within miles or km). Bottom line, I practically never brush.