Unfortunately, I have to report that while version 22.2.1.234.1810 has somewhat improved in terms of autocompletion issues for table and column names, the regression bug (as compared to 21.4.3.063.0100, where autocompletion is fully functional) still is not fully fixed:
In 22.2.1.234.1810, autocompletion works fine only if tables and therefore columns are defined in the local schema.
In case tables are visible through a synonym (regardless whether public or private synonym), autocompletion of column names still is broken.
I don't understand why such an important feature as autocompletion in terms of usability is not properly tested for correctness before Oracle releases SQLDeveloper versions to the public.
You have now repeatedly missed to fix this important issue - basically, all releases of SQLDeveloper after 21.4.3.063.0100 are completely unusable if you need autocompletion to work fine in synonym scenarios, too... :-(
Please finally fix this fully and release another build asap...!!!
Many thanks for listening!