Not a bug.
Those maps are not all meant to be linked.
crisis1 and
crisis2 are separate releases. The author stated that crisis1 came out after crisis2, and although the end of crisis1 is the start of crisis2, it's up to the mapper to make a
trigger_changelevel correctly to the "next" map. Not for us to alter someone's creative work en masse.
hostage is completely different to
hostage2a/hostage2b.
grunts1 is completely different to
grunts2. Even though the description of grunts2 says it is preceded by grunts1, both maps have different authors and are over a year apart. Again like with crisis 1 & 2, the map authors decided not to link the maps together and it's not up to plug-ins to fill in gaps that aren't meant to be filled.
war/war2/war3 appears to be the same mission, but again it's up to the author to link them up when one map ends.