The mentioned PR for Geany is still not merged. It should be updated to use "Nim" instead of "Nimrod".
I figured out, for syntax highlighting it's enough to have a filetype configuration file, which uses the Python parser. I have uploaded this file to [https://github.com/trustable-code/geany-nim-filetype](https://github.com/trustable-code/geany-nim-filetype)
