I would say that the Ciampino event mentioned actually reflects very positively on Ryanair and the crew concerned. I have a high degree of confidence in RYR safety: the aircraft are new, very well maintained, extremely reliable and the initial and recurrent training of the crews is first rate.
Cabin crew forgetting the name of the destination is insignificant. They might visit 30 different airports in a month and so it's quite likely that they might have to pause for thought mid-announcement. In fact some of the juniors I've met take very little interest in their destinations at all. They turn up to the crewroom at the appointed time, do as they're told and work the cabin exactly the same as any other day. The actual destination will not be at the forefront of their minds because to be honest, it almost irrelevent to them.
As long as the flight deck crew know where they're going! That's said I can't pronounce the names of half the Polish destinations, so my PAs are probably the same!