Mod version: 2.1.3
Forge: 36.0.9
MC: 1.16.5

JSON:

{
    "category": "Twitch_3rd_party",
    "name": "WAYTOODANK",
    "url": "https://cdn.betterttv.net/emote/5ad22a7096065b6c6bddf7f3/3x",
    "type": "emojiful:emoji_recipe"
}

This is an animated emote which isn't animated or even shown in MC.
Other BTTV emotes are just like PNGs, they are just not animated. Example:

{
    "category": "Twitch_3rd_party",
    "name": "DonoWall",
    "url": "https://cdn.betterttv.net/emote/5efcd82551e3910deed68751/3x",
    "type": "emojiful:emoji_recipe"
}

Try using https://cdn.betterttv.net/emote/5ad22a7096065b6c6bddf7f3/3x.gif with the file extension

It works. If you don't plan to fix that you don't need the extension, you could close it :)

It needs the extension as reference.