I don't see it as a misread of the 5E text. Calm Emotions does specify that it can cause all targets to become indifferent to hostile creatures as one of the effects. The main difference in the book text is that Calm Emotions is restricted to Bard, Cleric (a bit weird that a mass control spell is available to Clerics earlier than Wizards) and when any of the affected targets is attacked, it breaks for the whole group. Hypnotic Pattern is Bard, Wizard, Warlock, Sorcerer and each target is affected individually, so you can pick them off one-by-one.
Haven't booted up Solasta yet, but it seems like they implemented it faithfully reading the book text versus the game text.