As far as I can tell, only devs are the moderators, so outside of Aussie hours chat is susceptible to becoming a cesspool until they wake up. While this is bad, I don’t think there is a way Gems of War can protect your daughter from offensive content. Many games are in this boat, and it’s why many games simply don’t implement chat.
There is no way to reliably and permanently ban a person because there are many easy, legal, and often free ways to manipulate one’s IP. About all that works is having 24/7 moderation that reacts quickly so it’s well-known it’s not fun to throw yourself against them. (I don’t think we will ever/quickly get a large-scale moderation staff. I get the feeling the only moderators are devs, and players can’t be “promoted” to moderators without also giving them dev powers.)
In addition to that, moderators can only react. So even if we had moderators, people have to say nasty things in order to be punished for it. That means even if the people are banned, and the moderators manage to delete things quickly, your daughter is still going to see the mess as it happens live.
This is why many games that do have chat have a warning, “Player experience can change with online interaction.” It’s a cop-out acknowledgement that people can be jerks online and while the rating of the game in general may be all-ages, Bad Things can be found occasionally in the parts where moderators have to react to it.
It would be kind of nice if GoW interacted with parental controls and let you block your daughter from global chat. Nintendo Switch has this kind of feature, I’m sure XBox has it, right? As far as I can tell, Gems of War doesn’t interact with any kind of parental controls on any platform, and some platforms don’t even have the concept.
The best substitute is liking the same games as your kid and playing them together. Me and dad played the heck out of NES games when I was a kid, and I was kind of sad when as I grew up he had less time to spend on them.
So in short:
Gaming in general does a bad job of handling this and educating parents. Outside of the Switch I’m not sure if many consoles have a concept of “let parents help control how their children can interact with the game”. Even with rabid moderation, kids are going to see some nasty stuff. So any game with front-and-center chat and no parental controls should be a major red flag.