OBAS hostname and hostnames of PA nodes registered in OBAS were changed.
Is it a way to configure redirect from old hostnames to current ones in OBAS?
There is no special method in OBAS which allows to make redirects from an old hostname to a new one. Please use standard DNS ways: create CNAME records and aliases.
The same is true for PA hostnames.
The only difference is that there is a possibility to create brands. More info can be found in Branding Guide, Plesk Automation 11.5