Instead of 5 tables, really should just be 1 table with another field for category (cord, fabric, montage, packing, profile).
Then 1 query can serve as the report RecordSource.
The single table structure can be emulated with a UNION query. There is no designer for UNION query, must type or copy/paste in SQLView of query builder.
SELECT zlecenie, user_ID, time_cord AS time_enter, date_cord AS date_enter, quantity, "Cord" AS Category FROM tblCord
UNION SELECT zlecenie, user_ID, time_fabric, date_fabric, quantity, "Fabric" FROM tblFabric
UNION SELECT zlecenie, user_ID, time_montage, date_montage, quantity, "Montage" FROM tblMontage
UNION SELECT zlecenie, user_ID, time_packing, date_packing, quantity, "Packing" FROM tblPacking
UNION SELECT zlecenie, user_ID, time_profile, date_profile, quantity, "Profile" FROM tblProfile;
Now use that query like a table in another query to do the time calculations. Make that query the report RecordSource.