why not 'I will go again now'?
Because of the directional -n at the end of reen. I think that "I will go again now" would be translated by "Mi iros ree nun" or "Mi reiros nun".
Sounds reasonable and rather subtle when spoken out loud followed by 'nun'. Thanks!
i think that "reen" is just "re" and "en" merged, which means literally "again in"
In fact, it comes from ree + n = re + e + n, meaning “return”. Check out what PIV-o says about that ambiguity.
For the translate to Esperanto exercise would "Mi reiros nun" work?