I think they recognize brown as a color now... I would definitely say sealy brown
Her boy is clearly red based - regardless of shades, bays will always produce a mahogany tinge whereas chestnuts will remain "reddish". His uniform reddish hue and golden highlights indicate to me he's definitely not black based.
Here's a perfect example:
Top Line Quarter Horses
At first glance, almost everyone would assume she's a bay, but she's actually a liver chestnut with a dark mane. The second photo gives away her true color with that shimmery red tinge and non black legs.
Browns are almost exclusively a very dark bay, so dark that the black legs seem to disappear, hence the years of confusion between brown and dark bay. They will always have a very flat black or mahogany tinge.
His tinge is very blatantly black chocolate colored with tinges of mahogany on his points.