If you get stuck, you can always use the 100% walkthrough video. The link can be found on the Itch.io website of this game.
For the next projects I don't need any help because they will be very small.
For Bobo 2 which comes after that, I can't estimate it yet.
Overall I think I need the painting and composing in between to recover from designing the hundreds of rooms. I think I could use help decorating or even creating some rooms. However, Game Maker doesn't allow that so easily, because rooms can't be transfered so well. Unless anyone around here knows a good solution for that problem.
This is one of the reasons why I wanted to switch to Unity. Learning the new programming language was very easy and it was fun to use. Unfortunately the manual/documentation was not as good as Game Maker's.
I had problems figuring out how to calculate complicated collisions, because unfortunately all the tutorials used prefabricated collision systems and that was too inflexible for me. That's why I didn't get any further. I had already programmed a pretty good foundation, but at that point I wondered if the transition to Unity would take too long. Because I have a lot of plans, I stayed with GM (for now).