As a progression mechanic, Ex Nihilo Ascendio allowed emptying and filling wood crucibles and barrels with glass bottles and water bottles. Without that ability, the clay bucket becomes much less useful if you're playing in a non-rainy biome because it's not possible to reach clay without at least one barrel of water. And without support for glass bottles, the only way to move water from the crucible to the barrel is to reach an iron bucket (or some kind of fluid pipe or other clay recipe in a broader modpack, which usually requires similar or better materials)

Additionally, it was possible to fill crucibles from a bucket or water bottles to use as rudimentary fluid storage.

Ya, I used 4ths to avoid the rounding issue

I like this suggestion, I'll see how the water bottles were handled. I do not plan on making the crucibles usable as fluid storage, since you have the barrels for that purpose.

For more context, this feature seems to come from Ex Deorum rather than Ex Nihilo Adscensio. A single water bottle takes 1000 mB from a wooden crucible and adds 1000 mB to a barrel, carrying 1000 mB in a single bottle. However, for balancing that is closer to vanilla, I want the bottle to transport 250 mB at a time. That means 4 bottle refills = 1 bucket, instead of 1 bottle refill = 1 bucket from Adscensio. Let me know your thoughts!

That's fair enough. It's probably only going to be used to get the first bucket of water from the crucible to the barrel since you can then make clay and get a porcelain bucket. It's probably not a huge balance issue and slightly easier to implement, but for reference, most mods (and vanilla minecraft) treat a water bottle as equal to a third of a bucket. I'm not sure how they handle the rounding, but since water is generally infinite anyway, the discrepancy between 1/4 and 1/3 probably isn't a huge deal.