Base information

• Minecraft version: 1.12.2
• Mod version: 2.3.13.306
• Minecraft Forge version: 14.23.4.2759
• Mod Pack: In-Dev pack

Crash report

N/A

No Crash, simply trying to figure out IF it's possible to add Tinkers' Construct toolparts as ingredients with CustomFusionRecipes.json So far I've tried -
"tconstruct:pick_head,1,0,{Material:[stone]}",
"tconstruct:pick_head,{Material:"stone"}",
"tconstruct:pick_head.withTag({Material:"stone"})",
and none of them seem to work. Am I terribly mis-reading the instruction file? or is this something that's going to be trickier than the usual .nbt tagging?

You should be able to use "tconstruct:pick_head,1,0,{tag}" but you will need to use the exact NBT tag. To get that you can use "/bcore_client nbt" while holding the item. (it will be copied to your clipboard)

Aha, that'll be useful. Thank you!
(I've been using '/ct hand', since i'm using CraftTweaker, and that seems to be a bit, uh, specialized for the mod.)

And of course, the root issue is my inability to follow proper formatting in a .json... >.<
Last item in any list DOES NOT get a comma at the end!

Actually, even with formatting corrected, the recipe still doesn't appear to be working properly. With proper nbt tag (from the bcore command), this is what I end up with:
"tconstruct:pick_head,1,0,{Material:"stone"}"
Notepad++ appears to think the actual material type (between the extra "") is not a valid portion of anything, like it's only picking up on "tconstruct:pick_head,1,0,{Material:" and maybe "}" at the end.

::Edit::

For reference sake, here is the entire recipe that I'm actually trying to add, simply as a test to see if TCon parts could be designated properly. Perhaps you can see something I'm just missing:

{
    "mode": "ADD",
    "result": "draconicevolution:wyvern_pick",
    "catalyst": "iceandfire:dragonbone_pickaxe",
    "energy": 10000,
    "tier": 1,
    "ingredients": [
        "tconstruct:pick_head,1,0,{Material:"wyvern_plustic"}"
    ]
}

If that is your entire file then it should actually be this.

[
    {
        "mode": "ADD",
        "result": "draconicevolution:wyvern_pick",
        "catalyst": "iceandfire:dragonbone_pickaxe",
        "energy": 10000,
        "tier": 1,
        "ingredients": [
            "tconstruct:pick_head,1,0,{Material:"wyvern_plustic"}"
        ]
    }
]

Just make sure thats in config/brandon3055/CustomFusionRecipes.json
There should be an error in the log somewhere if it fails to load. Feel free to post your log using gist or a pastebin like service.

one of several recipes I'm adding. Everything else loads/shows properly in JEI. <- No it doesn't, when flawed recipe is in. otherwise it's fine.

Error section from my latest log: https://pastebin.com/dQa2zZW9

Unterminated array at line 263 column 47
Cannot help you any more than that without taking a look at your entire json

Ok so figured it out. Just a little quirk of json you need to escape quotes inside a string like this

[
    {
        "mode": "ADD",
        "result": "draconicevolution:wyvern_pick",
        "catalyst": "iceandfire:dragonbone_pickaxe",
        "energy": 10000,
        "tier": 1,
        "ingredients": [
            "tconstruct:pick_head,1,0,{Material:\"wyvern_plustic\"}"
        ]
    }
]

Excellent! Muahaha!