While you're technically right, "grandchild" is not specific enough. "Minha neta" can only be a girl, so it's best to use the corresponding female-specific word.
You can still report it and have the creators talk about the issue.
Am not opposed to this, but 'child' is regularly used as correct translation 'filha' and 'filho' (instead of the more precise 'daughter' or 'son), so I guess I'm mostly pushing for consistency.
I've been practicing Portuguese for a little more than a year on here and I don't believe I have seen 'neta' allowed to be translated as the genderless 'grandchild'.
In another sentence 'esta..'.is translated as that. How can I understand why now is translated as 'this'?