The nut on the end of the wax unit op rod, sets the SV position relative to the wax unit temperature. If the wax unit & its lever brass bearings are operating correctly it should NEVER need adjustment. If the wax unit is NOT operating correctly you can adjust this nut to compensate, but it may not cure your issue. If I were you I'd measure the rod protrusion length, then remove the nut & brass bearing & clean it as it looks like it may be corroded! Reassemble after cleaning & test again.
All the wax unit does is push pull the SV (choke) lever based on the coolant circuit temperature. When cold it closes the choke to make the AFR rich, when warm it opens the choke to allow main air control for idle to be by the SV/throttle plate idle screw setting. So if engine cold idles as expected (2-2.5k/rpm) then increases rpm when engine reaches nominal operating temp, the wax unit/SV plate is NOT returning fully to the Open position. The ECU does NOT have a monitor for WAX/SV position, but does have an engine temperature monitor for AFR compensation, hence the high idle speed.