Currently there is one entrance to all the dungeons and you use a menu that pops up when you walk close to the entrance to select which dungeon you want to enter.
This doesn’t work very well and it breaks the immersion a bit.
Instead you should do something similar to how tradu mines was, you enter one portal and get into a room with multiple dungeon entrances. Doesn’t have to be massive like tradu was, just having something the size of the inside of the tree would be enough to fit at least 4 dungeons.