[Indigo]

Sad, still doesn't work.

Perhaps I should use a new approach, maybe work some INI file within the Data/INI/Object directory?

[Dibelius]

you've have doubled the KindOf tag. I haven't realized that.

at the top you have:
KindOf = PARACHUTABLE SELECTABLE

and at the bottom:
KindOf = PRELOAD SELECTABLE CAN_ATTACK ATTACK_NEEDS_LINE_OF_SIGHT CAN_CAST_REFLECTIONS INFANTRY SCORE PARACHUTABLE

btw:
you should delete "CAN_ATTACK ATTACK_NEEDS_LINE_OF_SIGHT INFANTRY SCORE"
otherwise INFANTRY and SCORE will count the crates as lost units with an EVA event "Unit lost!". And crates can't actually attack something