I tried to summon a particle with the name "fallingdust" via an AreaEffectCloud (AEC), very likely with the wrong command (as I don't specify the type, like sand, anvil..), but it does not show the default "mobSpell" particle which seems to always show up with wrong particle names.

Steps to Reproduce:
Use this summon command:

/summon AreaEffectCloud ~ ~1 ~ {Particle:fallingdust,Radius:2f,Duration:600}

It says "Object successfully summoned" in the chat, but nothing shows up.

Use e.g.

/summon AreaEffectCloud ~ ~1 ~ {Particle:fantasyname,Radius:2f,Duration:600}

and it will default to its regular mobSpell-particle.

Testing blockcrack particle is successful with an AEC, example command (proof screenshot attached):

/summon AreaEffectCloud ~ ~1 ~ {Particle:blockcrack,Radius:2f,Duration:600}

blockdust particle doesn't show up at all as well (proof screenshot attached)

/summon AreaEffectCloud ~ ~1 ~ {Particle:blockdust,Radius:2f,Duration:600}

iconcrack particle does show up (proof screenshot attached)

/summon AreaEffectCloud ~ ~1 ~ {Particle:iconcrack,Radius:2f,Duration:600}

AEC with fallingsand probably needs to have an ID of the block added to the command to show the particle effect, but in any case the above command should show at least the mobSpell particle, even though it might be likely the wrong command }=)