https://dbfiddle.uk/?rdbms=firebird_3.0&fiddle=37ada2e7f3d90cbb3af638268bac67cc

create generator counter ==>> unsuccessful metadata update CREATE SEQUENCE COUNTER failed There is no privilege for this operation 

create procedure TMP ==>> unsuccessful metadata update CREATE PROCEDURE TMP failed There is no privilege for this operation 

since you isolate user access on files level, hopefully limiting External Tables and UDF's too on databases.conf level, then perhaps you can grant `RDB$ADMIN` role to the fiddler user, and also request that role during database connection?


https://www.firebirdsql.org/rlsnotesh/rnfb25-admin.html#rnfb25-prvlgs