You say facts ... but those are just presumptions both ...
1) Lenore built a way for her automaton to kill her.
Lenore build a "kill" phrase to her automatron ... that is all fact we know.
To say that she implemented it to "kill her" is just another theory.
And i feel the urge to mention that nothing in game that i have seen supports this theory. :-/
One thing does, as mentioned by the OP: Bernard will try to kill the player upon hearing the kill phrase
even if he thinks the player is Lenore. If she designed the phrase as a defense mechanism, perhaps to trap prying intruders, that seems like quite an oversight. In fact, given that she lived alone, she's the only who would've known of the phrase. That makes her the likeliest person to die from it.
2) She had the exact ingredients in her lab to brew Omeluum's potion.
There is many other mushrooms in her tower ... and not just mushrooms, but also flowers, crystals, sussur tree and lots and lots alchemical equipent ... Lenore was quite obviously experimenting with those things ... but we dont even know if she was brewing Omeluum's potion ... nor if she even knew about the posibility.
No, we don't. Be we do know she studied anti-magic fields, we know what the intended effects of Omeluum's potion are, and we know she had the ingredients to make it. Keep in mind those are dangerous ingredients to have around for no reason. If she wasn't using them, she would have probably gotten rid of them. Even if she didn't brew Omeluum's exact formula, it's plausible that a potion with those ingredients could have a similar effect.
I'll concede that my hypothesis fills in some of the gaps with suppositions. But there can be no doubt as to the kill phrase's intent nor to the presence of cultivated Tongue of Madness and Timmask Spores in the tower.
The defense rests.
