Seen it, but Fronius is not a make I've worked with and of course all manufacturers use their own acronyms so I may know SFI as something else in a Fanuc system for example.
SFI Is "splatter free ignition' on the manual settings.
I guess it works exactly the same on a robotic.
It feeds wire until it detects the arc starting then slows down / pluses / juddering the wire feed until the arc is fully initiated. I guess it works by not feeding in enough wire to give any excess material to splatter with.
SFI Hotstart
Same thing but with hotstart.
Hotstart might be what you would call 'coldstart' as it adds extra power at the start of the weld so useful for aluminium etc.
It's adjustable so can also be used to make some nice welds on steel.
Wire retract. I'm not sure. On the manual machines some of the feeders have a wire retact button. That pulls the wire back into the torch by just under the set stickout amount. I'd guess on a robotic it would be used to retract the wire at the end of a weld. This would be useful to prevent the wire touching anything as the torch moves to the next operation or if the torch teavled back over the area that had just been welded it would prevent the wire dragging over the newly created weld.
It would probably be a good idea to enable it at the end of the weld as it would prevent wire sticking yet enable you to keep the torch in the same place for some postflow gas coverage.