Not sure what is wrong with this but when trying to get particular mobs to spawn, I can get one, but not both.

potentialspawn.json

[
{
"dimension": 10,
"block": "abyssalcraft:coraliumore",
"mobs": [
{
"mob": "abyssalcraft:depthsghoul",
"weight": 3,
"groupcountmin": 0,
"groupcountmax": 1
},
{
"mob": "abyssalcraft:abyssalzombie",
"weight": 8,
"groupcountmin": 1,
"groupcountmax": 1
}
]
}
]

spawn.json

[
{
"dimension": 10,
"mob": ["abyssalcraft:depthsghoul", "abyssalcraft:abyssalzombie"],
"block": "abyssalcraft:coraliumore",
"result": "allow"
},
{
"dimension": 10,
"mob": ["abyssalcraft:depthsghoul","abyssalcraft:abyssalzombie"],
"result": "deny"
}
]

Split your potentialspawn rule in two distinct rules. It might be that you cannot combine it like that

I have the hardest time with json syntax.

Do you mean like this?

[
{
"dimension": 10,
"block": "abyssalcraft:coraliumore",
"mobs": [
{
"mob": "abyssalcraft:depthsghoul",
"weight": 3,
"groupcountmin": 0,
"groupcountmax": 1
},
{
"dimension": 10,
"block": "abyssalcraft:coraliumore",
"mobs": [
{
"mob": "abyssalcraft:abyssalzombie",
"weight": 8,
"groupcountmin": 1,
"groupcountmax": 1
}
]
}
]

I'm not understanding how to make this happen, nothing that I'm trying is working.