I cant believe this discussion actually went on to multiple pages.
On side note, Hashirama said "My little brother was killed." Now I thought Tobirama was his little brother too. Since he said "my little brother was killed" instead of "one of my little brothers was killed" It must mean that tobirama is not his real brother.
Did you see what I did there? If you misinterperate things things, you can spin in any way you want.
There was no translation error. Madara "HAD" 4 brothers at one point before one or more of them were killed. We know that Izuna lived past that age, so at most 3 of his brothers had died at that point.
I hope we can lay this to rest as a reader misinterpretation