The pacing is certainly all over the place. Going from diary --> little broster stealing stuff and getting confronted --> diary again. That's so clunky. And then she just said I will tell you next time instead of just telling them right away. That'`s... really weak.
That aside though, whatever was yuri!Marika searching for? A secret portal to another world? lol
Little broster at the very least introduces some stakes towards the solution of letting both Marika's stay in the opposite worlds. With Kazami's reactions it's clear that she wants Marika to stay, but family and friends are still going to miss the old versions. Marika insists on returning and I can't fault her for it. At the very least she should have a way to say goodbye to her original family and cleanly break it off with whoever she was dating before.
It would also be interesting if they found a way to switch worlds whenever they want. That would probably be too easy though.