Geany indentation is very simple so that it will work for as many styles and languages as possible. As such it does not "know" anything about your language or the style you are using.
Building in indentation knowledge for all supported languages and all styles of those languages is beyond the scope of a lightweight IDE.
Running external language formatting programs is covered in the [Geany manual](http://www.geany.org/manual/current/index.html#sending-text-through-custom-c...) or userscan also write plugins to access formatters such as the one at https://github.com/codebrainz/code-format.