just a speculation but...

could Lila/Cerise's wish be just a simple thing?
after going through all the seasons of MLB, I found out that Lila had just one motive the whole time-
TO DESTROY LADYBUG AND MARINETTE
and she just wants to do that... and nothing more

in London, Cerise found out that Ladybug and Marinette were the same person so she had a plus point of evicting both of them in one single shot...and that was by using the WISH to help her attain her goal.....

idk what you gworls think...