I might have a bit of insight on that : in the 0.26 version I also struggled to proc the event for Gina.
With a bit of save editing magic to play around with flags, I tried a couple things, seems like having the lactation powder "too soon" (I bought it the moment I saw it in the shop), there's some checks that don't trigger properly.
I managed to progress Gina's story up to the current end (all events green) when I waited for the game to tell me to go to the occult shop to progress
Edit : Aaaand I just saw that this particular bug was fixed in 0.27 ^^"