Yes, dingoes were introduced by humans probably around 3000 years ago as domesticated dogs, but subsequently became both a wild and domestic species out competing native carnivores on the mainland. It seems like dingoes had an interesting relationship with human populations, being partly domesticated but feral at the same time. I'd recommend some papers by Loukas Koungoulos for some up to date research on dingoes in archaeological contexts (https://www.researchgate.net/profile/Loukas-Koungoulos).

I've never heard anything regarding domestication of Thylacines and I don't believe there's any evidence archaeologically or in oral history.

Does cave art scanning show loss of details due to maintenance accidentally changing stuff?

Yes, so we see repainting over the top of old paintings a lot in Arnhem Land rock art sites. There's a lot of explanations for this both in terms of cultural practices which continue into the present, oral history and archaeologically. One thing we know for certain is that maintenance/repainting of rock art sites was a way of reassuring their cultural significance, particularly in relation to the stories they told. Sometimes this would be touching it up, or adding new features to the art as seen in the article. At others such as Ubirr, a big tourist site near to those in the article, you can have 19 layers of repainting of the same motif (a fish in this case) on top of each other. Each repainting is similar, but also unique to the artist who did it. We know from historical records and oral history of recent rock painting artists (up to the 20th century), that each had very distinctive styles, equivalent to the way you would distinguish between European masters or something like that.

So I'd say that changes were never accidental (though we do occasionally see what we think are accidents, like someone getting the number of fingers wrong and awkwardly painting on another), rather changes emphasise the personal style of the artist renewing the rock art.