I gues this might be due to the fact that by config of your domain the DefaulServer (Admin) is assigned the SOA-MGD-SVRS servergroup. While you retargeted the components, you probably have a domain where these groups do not match.
your new soa_server(s) should have the SOA-MGD-SVRS or SOA-MGD-SVRS-ONLY (when you have a separate WSM_PM cluster/server) server group.
You could try to adapt this in wlst using:
setServerGroups("DefaultServer", ["WSM-CACHE-SVR" , "WSMPM-MAN-SVR" , "JRF-MAN-SVR"])
See for a script to create a FMW domain, where I got this from: Darwin-IT: Scripted Domain Creation for SOA/BPM, OSB 12.2.1