"How long should I wait for Penumbra?"
If Corinna is dead, Penumbra will hang out in the park, but will not talk to you.
To get Corinna back as a merchant (this will not let you complete any quests she is involved in);
see
Reviving dead NPCs /
Fix for giving Corinna a fake Talking Tree branch"Well, even one try to move the grail causes mummys' attack. I have 90 points of strenght. How much will I need?"
'Strength' was being used generally, as in a higher character level with more hit points and better equipment.
