Magic in this isn't very good, every time a giantess uses magic it's an asspull.
"Don't worry, nobody can hear our conversation with magic"
"I can crush you and drain out your blood but, you'll be fine with magic"
"you won't get digested inside me because of my magic"
"Say the passphrase and I'll find you with magic"
Number 2 has been explained in multiple routes as the soul link, with dire consequences for the tiny it's casted on if the giantess loses interest. Hell, they even go into detail about the way souls interact with magic many times.
Number 3 is something you could probably achieve IRL with pills n stuff and suffer indigestion and what not later.
1 and 4 are kinda shit, 4 is basically the Voldemort name spell with different conditions, and 1 is so generic that nobody will explain it. The bigger problems come with things like Yakuu and other demons (even Zanna in the side stories) having convenient asspull shadow magic that can hold people, dissolve to misty darkness, form into clothing, and goodness knows what else.
Oh, and the Queen has the f****** Sharingan apparently, and can see everyone and everything near her. Can't wait for her to get other poorly explained eye powers to support her right to rule....wait, that's exactly what happened in Naruto