Do Wiccans do rituals in Latin? I'm not a Wiccan but used to be on a path that would be considered pagan/occult (or possibly Satanic, depending the level of ignorance of the person describing it). I've known quite a few Wiccans over the years. I don't recall anyone (of any path) doing magick in Latin (unless the original's Goetia's in Latin? - Wiccans probably wouldn't do that kind of magick though.) Hebrew's a common language to use, due to influence from Qaballah (Jewish mysticism). Given that Wicca's a reviving of North-West European pre-Christian religions, I'd say English and the Celtic languages are more likely. The Wiccan Rede is in English, and other Wiccan expressions such as Merry Meet, or So Mote It Be. The Wiccan festival names are in NW European languages (i.e. a mix of different ones), including Celtic languages, (like Samhain, which comes from Irish). There is some Latin influence on pre-Christian religions, due to the fact that the Romans got there long before Christianity, but Latin is the language of the Church of Rome. Given that during mediaeval times the Church of Rome executed people they accused of witchcraft, Wiccans aren't terribly keen on them and doing rituals in their language seems a bit unlikely.
Granted that pagans are a very ecclectic bunch, virtually impossible to classify, and there are different branches of Wicca and each coven will have its own way of doing things, and covens often keep their rituals secret. So I'm not saying no wiccan ever did any ritual in Latin ever. I'm saying I don't think it's typical and it's certainly not default.
Latin is going to sound churchy and Harry Potterish. Going by the Wiccans I've known over the years, they like the Harry Potter stories but would be the first to point out that it's complete fiction and real Wiccans are nothing like them. So anything that portrays Wicca as being Harry Potterish isn't likely to go down all that well.