The reason why the hive mind has a slasher body is because of the body being defined in the general section, not in specific castes. It needs to be separated from the hive mind caste itself, by using [SELECT_CASTE:SLASHER_FEMALE], [SELECT_ADDITIONAL_CASTE:SLASHER_MALE], so on and so forth.
However, you have defined the castes a bit lower than the body_detail, so you need to move it above the bodies.
For ease of caste selecting, just add [CASTE:XXXX] above the body details and replace the original caste tags with [SELECT_CASTE].
Next, add SELECT_CASTE to everything except the hive mind and add your body_details.
[CASTE:XXXX]
so on and so forth
[SELECT_CASTE:XXXX]
[SELECT_ADDITIONAL_CASTE:XXXX]
[SELECT_ADDITIONAL_CASTE:XXXXX]
[BODY:DEFORMED:2EYES:2EARS:NOSE:HUMANOID_JOINTS:NECK:SKULL:5TOES:MOUTH:FACIAL_FEATURES:TEETH:RIBCAGE:BLADES]
[BODY_DETAIL_PLAN:STANDARD_MATERIALS]
[BODY_DETAIL_PLAN:ALTERED_TISSUES]
[BODY_DETAIL_PLAN:VERTEBRATE_TISSUE_LAYERS:SKIN:FAT:MUSCLE:BONE:CARTILAGE]
[BODY_DETAIL_PLAN:HEAD_HAIR_TISSUE_LAYERS]
and
[SELECT_CASTE:ALL]
to proceed with other tags.
Remember to modify it properly so no other tags except the slasher body gets defined in the castes.