So as I wrote on Github this concept of fluid amounts and fluid granularity has been discussed in length several times in several minecraft-related communities.
The issue always boils down to an acceptable standard that fits most peoples use-case and makes sense from a human-level base math standard.
The concept of 1 bucket = 1000mB is rather straight forward since it's all just a power of 10 or whatever.
So it's easy for people to do the math "oh okey so I need 32 buckets, that's 32 * 1000 so 32000.
The counter point is that the very granular nature of a system based around singular increments instead of measured objects is inherently less coherent when dealing with stuff like item/block to fluid conversion rations.
For example:
1 Block = 1000mB = 1 Bucket
1 Block = 9 Ingots
1000mB / 9 = 111.111111...mB
If we then divide it further into nuggets so
1 ingot = 9 nuggets
111.111111.../9 = 12,345679... mB.
So the suggested alternative is going to something more akin to a "imperial system" where things are tied to "in theory" objects and not singular units.
Aka 9 Nuggets = 1 Ingot = 1/9 Block
This means that if we establish the value of one core object, we can iterate it through-out for most cases.
For example:
1 Nugget = 16mB
1 Ingot = 144mB
1 Block = 1 Bucket = 1296mb
Through this we can easily establish that 1 bottle is about 1/3 block since 1 bucket of water in a cauldron yields 3 bottles.
So the value of 1 bottle is 1296/3 = 432mB.
We can also establish through block measurements that in theory:
A Slab (half a block) should be equivalent to 648mB.
A Pane (1/16th of a block) should be equivalent to 81mB (not accounting for the recipe).
If we do the calculation based on the recipe, a pane is worth about: 498mB (accounting for 1 block being worth about 2.6 panes).
Etc.
Once again as I said on the github issue the biggest issue with a suggested change like this is while it in theory "makes more sense".
It's changing a fundemental concept of how the modded fluid system has functioned for the longest system and uprooting the established status-quo of fluid recipes, values, tank sizes, etc.
And people will need time to get used to a change like that if it were to go into effect.
I'm not against it, but it's certainly something that needs proper deep discussion and at least a majority acceptance if it were to be applied.