Hey @iluxa7k -- nice to hear you liked Craftr! I'm still developing it actually. I just recently updated it. Craftr itself has changed a lot, and the C4D build module was updated for R20.
Craftr doesn't use the project tool but does invoke the R20 source preprocessor. I still use it over the project tool as it integrates in my existing ecosystem and I can compile for R19 and R20 without needing to keep multiple project files in sync.
Anyway, I won't be able to maintain Craftr intensively in the future, so if you create a plugin for R20+ only, I'd recommend using the project tool.
@jiceq What's the value of file_path? Looks like you overwrite your script with a C4D scene file.