To just the author and mods, unfortunately we cannot support this yet, as we don't have a "post author" pseudo-group. That is a good idea, though.
We did accomplish this via nodebb-plugin-support-forum, you could try this and see if it still works?
You're not able to change the routing in such a way, because then users whose names are only numbers cannot be accessed.
Best bet is to set up a rewrite rule in nginx to send users requesting