Is there any chance you could rework your loot-tables to follow the vanilla format internally? Currently, with the change to custom-formatted tables in the config folder, I cannot find any way to add an entry that references another loot_table (which I could do using vanilla datapacks before the change).

Specific use example:
TreasureBags by SilentChaos512, uses datapacks for setting up all the bags, loot for them, etc. He's also setup a function that allows for designating them in Loot Tables. With your current formatting there is no way to add these bags to your loot_tables (as they need the proper type .nbt added by the function).

Coming in update 1.5.0 :)