I found the mapping file named "Novation LaunchKey (keyboard).flmapping". I renamed it to "Novation LaunchKey MK2 (keyboard).flmapping" and now my MK2 keyboard seem to be auto-linked.Mixer control (Launchkey 25/49/61(MK1 Only)):
Turn off the first 2 'InControl' buttons for the faders and knobs and focus the FL mixer window. The 8 faders are auto linked to track 1 to 8 volume and the 8 knobs are auto linked to track 1 to 8 pan. Change the keyboard output MIDI channel to control the next 8 tracks volume and pan. Alternatively you can manually relink knobs and faders to other parameters instead.
Is there a reason why this isn't addressed and the page just says MK1 only? Is there some incompatibility between the MK1 and MK2 that makes the mapping files for one not completely compatible with the other? Why not include a mapping file for the MK2 models as well?