forge 1.18.2. I made a datapack to alter the stronghold loot tables and found out the hard way you apparently ignore the vanilla ones completely in favor of your own?

Unfortunately that is the case. We re-added all vanilla loot tables starting on 1.19.2

Update, even the ones that do use vanilla loot tables (like the crates in storeroom) use the vanilla loot table and ignore changes made via datapack

I think that means your data pack isn't applying properly then. Chest loot tables are handled by reference, so any changes made to that loot table will be reflected in that chest.

The loot table definitely works, and is properly generating in other structures that use it, but not yours even when referencing the same vanilla loot able. Perhaps this only applies specifically to stronghold corridor though?