Of more interest is how fast (slow) is it, remembering it runs while editing, will Kotlists get big pauses?
If the table above is valid and from what I remember the C parser speed is about 50MB of sources per second and the kotlin parser is about 100x slower than the C parser, it gives us 500KB/s for kotlin. And the pauses should be just something like 0.2s not to be noticeable so about 100KB kotlin source files would be roughly the maximum for Geany.