ConnMan stores service profiles in /storage/.cache/connman/<servicename>/settings but the file is owned by ConnMan so it will ignore all changes made while ConnMan is running and may overwrite them at any time. So edits require you to either make changes through the connmanctl app, or you need to "stop > edit > restart" the service to make changes.
You can also try an LE11 nightly (back-up the current /storage/.kodi dir first so you can revert easily) as the nightly image has newer connman and also switched to iwd instead of wpa_supplicant.