Ken: I'm in shock.

Total and utter shock. Did you actually use the "I" word?
And you complain about me torturing poor Alt Clark
Complain? Oh, it wasn't complaining, it was more teasing.

If Clark has life too easy, it wouldn't be much fun to read.
You've set up an impossible conundrum.
Oh, my gosh! You DID use the "I" word! You! The Great KEN, lover of all things Herb Wellian!
She's doomed if they do and he's doomed if they don't. Herb sees no way to correct the timeline short of saving Tempus and that appears to be impossible.
Ah, but you and I know, that "nothing is impossible".

Perhaps there's another answer that doesn't require Herb's assistance.
You've hinted that she's going to give in to Luthor and that's not good.
Let's just say that things aren't always as what they appear to Herb (on that front and others). Thanks for reading.