Hm, actually there doesn't seem to be any need at all currently to *build* kdenlive against mlt 6.2.0. Just install it and it will be used. Or is there a problem with that? I.e. is mlt 6.2.0 not compatible enough with 0.9.8? If there are any features missing, it's because they are not implemented yet in kdenlive, not because it is built against an older mlt... At least that's how it looks to me. Releasing mlt 6.2.0 as update for Leap might still be a good idea though (AIUI it fixes a crash in kdenlive), but that's for the mlt maintainer to decide I'd say.