Seems like currently there is basically no regular spawn heroes for Cronley that can actually drop their MIs
I was farming Cronley rings and repeatedly got multiple “nighblade”/murder themed heroes and got surprised they never dropped Murder MIs, so checked Grimtools
of the 7 Cronley gang MIs 4 heroes exist that can drop them, (3 of those are Bounty only spawns), and 3 of those 4 heroes (2x bounty spawns) drop the same single item Ascended Shoulder, the 4th (a bounty Hero) can drop Murder hood
Ascended Casque, Incendiary Casque, Incendiary Shoulder, Murder Epaulets, and Murder Breastplate has no heroes attached at all (not even Bounty heroes, and i don’t think bounty heroes is optimal in general)
I would suggest going over the various Cronley heroes and adding XY fitting themed armour MI to their respective heroes,
ex could be adding Murder chest/hood/shoulder to Nadra the Shadow, Serul Shadesong, Roman the Blade Dancer, etc for others/Incendiary and Ascended MIs to some Heroes (that isn’t fixed to bounties only 
)
It’s not just to make farming these items a little better (drop rate wouldn’t even have to be increased compared to champs/could be the same as champs), but to make it feel better/have the heroes seem more “meaningful”, when killing them just makes you question why it didn’t drop anything “when it seemingly should”, compared to other MI class Heroes