Did some basic testing

Place water in world: pass
Pickup water in world: pass
Right click place water into tank: fail

Place lava in world: pass
Pickup lava in world: pass
Transform bucket into charred bucket:pass
Set player on fire:pass
Right click place in tank: fail

Creative tab renders only the acacia version of other fluids. Consider making oak the default texture. Reason: oak is the most popular wood to start with om most packs. Also many pack makers pull items from creative tab to run the " /mt hand " command on.

I noticed you plan to add a milk block. Placing milk in world will not be possible from a bucket because of conflict with right click drink action. Will test dispenser during next test session.

For the tank used in above testing I used fluid vessel from embers. Will do more thourough testing at next time.

For the milk bucket I would suggest doing the shift right click to place in world. This way you have less code to write.

Another change that would be really useful for pack mackers is having the cactus green in the shaped recipe accept any ore dict with dyeGreen. Speaking from experience I made this change via minetweaker in my last pack via minetweaker.

Tank support does work for CoFH mods, so it might just be embers does not support fluid capabilities. This will be easy to fix as I can re-add the old API if it still exists in 1.10.

As for milk drink action, not too worried about this at the moment. As the buckets are designed for fluid transport more than anything else. I could add an alternative action to do drinking of fluids. For example, right click air or shift-rick click.

The creative tab is set as the first bucket found. So it can change as you add or remove bucket mods to a pack. Not going to change this as filled buckets is a bonus feature.

Anyways thank you for testing :)

Same amount of work either way.

As for the dyeGreen, almost all bucket recipes are moving to using any dye via ore dictionary. It may just not have been updated or a new build released yet.