Hm, it seems that you have to specify some local-address and remote-address in the /ppp secret or /ppp profile for the OpenVPN client even if the openvpn server runs in mode=ethernet (not sure whether it is a bug or a feature), but you may use already existing address as the local one so adding it should cause no real harm. It may help you to set netmask under /interface ovpn-server server to 32. However, in your setup you end up with an IP address assigned to a bridge port at server side, which is normally forbidden.
Instead of writing novels, post /export hide-sensitive. Use find&replace in your favourite text editor to systematically replace all occurrences of each public IP address potentially identifying you by a distinctive pattern such as my.public.ip.1.