Actually, they are based on Eggerland 2 - Meikyū Shinwa (MSX) and Eggerland (Famicom Disk System). I've converted and adapted all the stages, so you can play them in Eggerland Mystery without need to explore a giant labyrinth!
Of course, some stages are less difficult, as the first game of the Eggerland serie has some limitations : only 10 monsters of the same family in a stage, no advanced monsters (Leaper, Rocky, Don Medusa), no grass, sand or lava zones, slightly different behaviour of skulls and golls, no tricky stages. I let you find out the adaptations!
The file : http://eggerland.msxblue.com/EGGERLAND23.zip
The map with these 'new' stages : http://eggerland.msxblue.com/eggerland1b-map.png
The map of the original Eggerland Mystery : http://eggerland.msxblue.com/eggerland1a-map.png