Hi! This is not yet possible in a supported way. But it is possible by reaching into the internals.
table.table._engine.docmodel.get_column_rec("TableName", "Is_Valid").label
Similarly to the answer in https://community.getgrist.com/t/column-name-in-formula/2179/2 about getting the current column, the downside is that this is not public interface and there is no guarantee it will continue working in future versions.