The main problem is related on the title (and related with adding new dimensions with datapacks). To recreate this issue, download the datapack that I provided, and if you want you can create a world with that datapack to verify that it's currently working and adding a new dimension called "pru_eba". Then, go to the dimensions/minecraft and rename the pru_eba.json to pru_eba_.json, for example. Try to use the modified datapack and you will se that the new added dimension isn't working.