BucketStacker is a relatively simple plugin that makes buckets stackable up to 16, like their normal bucket counterpart.
Yes, there are other plugins that can do the same thing. Plugins like those stack items together, no problem. The downside to other plugins is that when buckets have more than 1 in a stack, they will empty out all the buckets and give one back in return.
BucketStacker manually reprograms buckets that have more than 1 in a stack to work as intended.
BucketStacker will still be able to stack buckets together when in creative mode, but they will not deplete, keeping the same Minecraft rules regarding buckets in creative.
There is one simple command, /stackbuckets, which does as it says, stacks buckets together (lava and water). /stackbucket's permission is "bucketstacker.cmd"
This is a problem with minecraft itself, and is not fix-able through BucketStacker. Right clicking again will fix the problem.
This is also a problem with minecraft. If I manually go in and increase the max limit of the items, it will create clone copies of items (client side) when trying to spread the buckets out in your inventory. Using the command is also easier for large quantities of buckets.
If you found a problem with BucketStacker, create a ticket and fill out a way to replicate the bug. Or, if you are lazy, you can just leave a comment. I will try to fix it as soon as I can. (If I am able to replicate the problem)