[Lava]

Oh, I've coded it long time ago. Now, that I look at the code, it may be impossible to just use console, because it's not just the match, but specific talks that will happen only if your character is an elf. In theory you may try:

C:SetGlobal("L#LannaRomanceMatch","GLOBAL",1)

And set these variables after the friendship is completed:

C:Global("L#LannaRomanceSituation_A","GLOBAL",1)
C:Global("L#LannaRomanceSituation_B","GLOBAL",1)
C:Global("L#LannaRomanceSituation_C","GLOBAL",1)


These variables are set during the elf-only talks.
Sorry, I won't be of much more help as I have the flu and that's just the only idea I have for now.