The Cairo modules are created because of the need to get to the native objects whithin the rest of the Gnome packages. I would otherwise have used the package written by Timo. When you only have to draw an image and save it to disk, the modules of Timo might be a better solution. If you want to have drawings in your widgets, the Gnome::Cairo package is better.
The modules are all generated from the C source code and the documentation refers specifically to operations in C. Most of it is converted on the fly into Raku types or Raku native types. Sometimes, however, there is a mention of an operation like for instance, referencing or un-referencing objects. Those parts must be investigated still to see what the impact exactly is in Raku.