It's a shame that the first portal doesn't work since the game looks so promising! I did experiment a bit in the first screen of the game to try to find some other potential bugs, with there being two:
1. When the player jumps from the highest platform and hits the ground, the space below the stage becomes visible briefly as the camera follows the momentum of the impact downward.
2. When switching between pages of the book, clicking on the first two options in rapid succession will cause the two to display at the same time over top one another.
One note about the aesthetic is that it seems like some aspects of it are different resolutions of upscaled pixel art, which seemed noticeable with the character portrait and UI, though I might just be misperceiving things. That said, the aesthetic looks great otherwise, so it isn't a huge complaint.
I hope the portal bug can be patched because the animations and glossary hint at it being an interesting game!