Qlik Sense allows column labels in the enclosing chart to be used in Expressions. These are frequently flagged by the Expression Editor as “Bad field name” even though the expression will evaluate correctly.
QSDA uses the Qlik Engine syntax checker, which is not aware of chart columns, and so will always flag chart columns as “Bad field names”. In QSDA 1.7.2 I have made an update to suppress “Bad Field name” errors for “bad fields” that match chart column names in the enclosing chart. Note that while this may not match what the Expression Editor says, I believe it is the correct choice and will give the most useful advice.