$X Tables Do Not Exist?
There is no such thing as X_$KSPPI. It is X$KSPPI. You have a synonym pointing to a non-existent object.

That synonym does not exist in Oracle databases, that was created by someone or something else.

Your attempt to desc sys.x$ksppi; fails if you do that any other user than SYS.

If your database could not access parameters, you would have a much bigger problem with more obvious symptoms.