Well, both plants won't necessarily require the same feed.. That's definitely the way
my magnesium issue showed. Possibly water the WW first, then add an additional 1/8-1/4 teaspoon Epsom to the remaining water before you water the Royal Haze..
I think the stretch looks great for an autoflower, especially under an LED - you want some stretch like that - but if your vertical growth has stopped, you can bring the light to 12" from the canopy. :thumbs
Never feed with every watering in dirt, all of the nutrients aren't used up between waterings.. I feed ~66% of the time (three waterings a week? water feed once, water plain once, water feed once)
Bring the lights in, get a little more Epsom in the water before feeding the Royal Haze .. see if it makes a difference,