First of all thank you!
The game definitely needs more balancing updates, the WIP status shows through a bit because of the difficulty spike from Cerelea onward. Level 9 was the intended recommended level for her, but I'm not too surprised the walkthrough author recommended level 14 instead, several people have been having issues with her. In her case, I also need to make the Wall Smasher mechanic more obvious through visual effects...! To be honest, even the forest should be easier. This is something I'll be working on in the next update.
This is completely doable to be clear, but it's obviously easier for me knowing exactly how the game works and what to look out for. Don't hesitate to just lower the difficulty instead for now, nothing wrong with that!
And, thank you for letting me know!