I Feel bad for them, so I’m thinking of new rules.
For the Dominus, maybe have his ability be a choice each turn between :
– give a <Cult Mechanicus> unit within 9” another canticle in addition
– +1 to hit for <Cult Mechanicus> / units within 6” but remain stationary
– reroll 1s to all <Core> units
Expand the Enginseer’s ability where if the model chooses a kataphron unit, it can ignore ap1
For the Tech-priest Warlord Traits, include the kataphron unit in addition to the Cult Mechanicus Core when interpreting
Finally revert the Kastelan’s phosphor weapons to all be S6 AP -2 D1 and remove the 5pts to take its arm mounts
or keep it and allow the datasmith’s gamma pistol to be a little more useful by granting reroll 1s to kastelan models shooting at the same target