I'm using the same keybind as you do.

The space one however, did not work well for me. It resulted too frequently in space not working at all. Supposedly it got matched as a combination with another key instead of a tap.

I recommend to apply a new rule, then test it out, then make another change. This way, you figure out which rule poses an issue.

There is one ruleset in Hammerspoon in the Github repo which I mentioned which -for me- makes it impossible to type cd. It always becomes c d