Elo (^^)/ made this so those who asked can be rest assured on the topic.
Like everyone else I know how hard and how salty things can be when trying to pull a Witch Riko... Even as a event hunter basically re-skinned of the original, element change and Bats swarming on 2nd skill activation her drop rate is really broken. Even myself I didnt aquire her thru pulling hunter draws with the Lottery Mouse.
This event (A Time'd Event) you can try your luck at pulling her and those who are I truly wish you the BEST OF LUCK (^^)/
BUT... I would recommend not wasting your Manda on a huge IF or MAYBE. The Time'd event comes around every once in awhile.
Do like I did and wait for the (Halloween Event) where she becomes available again to pull. Saving up your EVALUATION REQUESTS will pay off because her traces become available with the lottery mouse when cashing in those requests; and to unlock Witch Riko you only need 40 traces. Later as long as the developers havnt changed anything you only need her once, then you can transend her using standard Riko's.
And to those who didn't believe me, the picture posted shows that traces for Witch Riko are in fact available through cashing in EVALUATION REQUESTS. She has no ruins that I'm aware of, as far as I know those are the only 2 ways of getting her; the way I described being the most cost effective or at least Manda conserving.
Hope this thread helped and I wish you all the very best and BEST OF LUCK IN YOUR ENDEAVORS (^^)/
If you have any questions, dont hesitate to PM me. ^^