Going to be interesting..
I've experience with SU, LH and LX on their asian routes.
SU, as far as I can remember, don't have any local staff, but rather has 1-2 of their FAs able to speak (to some degree) the local language.
LH has local FAs (at least China/Japan destinations) which are actually forced to learn German, and their English is also good from what I can tell.
LX apparently only hired cheapest FAs they can find, very limited English skills, no German or anything else, often very rude. FAR from what I would expect.
From my personal experience, I would rate the system that LH uses as the best, followed by the SU system. LX _totally_ lost the plot, and I've mentioned it already to them a few times. They admit that it's not "perfect" (according to their own language) but they apparently won't change it. Which is really bad, considering LH can do it..
I hope Finnair will use a LH-like system, in that case.