There is one flight from Fes Morocco to Barcelona on April 27 on Iberia Airlines. It leaves 7:20 pm and arrives Barcelona 10:10 pm.
Is this a reliable flight? We need to fly the next day to Frankfurt - there are several flights on Lufthansa, but only this one flight out of Fes on Iberia.
There is no such thing as a reliable flight; any flight could be canceled or delayed so maybe you should leave on April 26 and give yourself an extra day more time to get Barcelona so you lower your risk.
Also there seems to be 3 direct flights operated by 3 different airlines on that day?
4:15 PM – 7:10 PM
Ryanair
1h 55m
FEZ–BCN
Nonstop
$92
7:20 PM – 10:10 PM
Vueling
Iberia
1h 50m
FEZ–BCN
Nonstop
$97
3:55 PM – 6:45 PM
Air Arabia Maroc
1h 50m
FEZ–BCN
Nonstop
$108
All flights/airlines are more-or-less as reliable/unreliable as any other. Iberia is a major airline. Flights between Morocco and Europe are routine, frequent, everyday milk-runs, just like flights anywhere else.
As Jazz says above, there are other options besides Iberia (be aware that flight schedules, particularly on low-cost airlines, are date-dependent, and most do not go every day, so check schedules carefully).
You should be able to check on-time performance for this flight or any other. Just Google "iberia airlines flight XX performance" (where XX is the flight number). You will find oodles of statistics.
