Version: 3.8.1 for MC 1.12.2

So I don't know how reasonable it is to bring this up, given that it is not really a bug, and that it only matters in conjunction with respective mods, and particularly as it might take comparably much effort to solve this issue, but I thought I'd still point out the underlying problem and bring up the question of if it should be solved or not.

So, the problem: If fluids from different mods are registered with the same name in the fluid registry, the results might be unpredictable and undesirable.
It would therefore be beneficial to either change the identifiers of The Betweenlands fluids in a way that makes them unique, e.g. "bt_rubber" or "swamp_water_bt", or to give the option to do so via the config file.

For example GregTech Community Edition unifies the fluid registry in a way that The Betweenlands' fluid rubber is replaced by GTCE's black vulcanised rubber fluid. This means that The Betweenlands rubber trees suddenly give this vulcanised GTCE rubber, instead of the unprocessed latex tree sap that was actually intended.
I suppose similar could go with other mods, and maybe with other somewhat common fluids like "tar" and "fog".

The problem in fixing this is of course that it would either need a way for loading the fluid registry names from a config file, or would need the names to be changed in general and for all players, necessitating an unpleasant and probably disproportionate effort in migrating to the new naming.
And I don't know if you'd be willing to put in the effort for such a fringe issue.