These are "popular" rather than folk dance tunes (I'm not using those words precisely, hopefully you see what I mean) so perhaps maximise cross rowing rather than the push pull on the row thing, to get a more continuous sound (I have no idea how practical that is playing this music on a DG melodeon). Then I would say there is a certain articulation that would help, based on contrast between staccato, detached and legato in different phrases/sections with a fair bit of detached playing. There is a you tube channel called bymarco fisarmonica where you can here a whole load of popular accordion styles that might give a feel. Then sometimes in a tarantella (which funiculi funicula is, kind of) you might hold onto the basses for longer than ususal but whether this sounds good would depend on the balance between left and right hands. Then finally, a very dry tuning would sound a bit odd, if you have a choice. Bear in mind I'm a terrible player.
Edit; I just read the title of the thread... The ornament involving playing the note, then the note a tone above it, then the first note, in a triplet, is quite common. Repeated notes, either on the beat or as a grace note just before the beat. Bits of right hand harmony in thirds. Maybe.
