With todays hotfix#21 out and as seen from the logs, MInthara's reactivity got fixed!
It's the reactivity bug where Empereor/illithid was spoiling and overriding the rest of her reactions.
Least in my old save which was started when patch 5 and hotfix 16 was released, Minthara is so far working as intended with her reactivity, so happy to share this and eeger to hear from others how you experience MInthara now. laugh

Going to start a new game from scratch and see how well it works and whether anything else needs attention.