Welp.
I used to translate from Japanese to English as well and see problems like this one too, in the past. It is indeed nothing wrong if someone wants to translate for fun and improving their grammar, but there is also nothing wrong to give a notice to the previous translator if one is going to translate the same series. It might seem as a simple matter to some, but for some others it might be a serious one. Just contact the previous translator in order not to let any misunderstanding happens. Of course, we are doing this for fun because we pirate, so there is also nothing wrong to join forces or take turns to translate if we are too far from the latest chapter, or simply release both versions.
As a fellow translator, I thank you for the translations and hope this case is solved asap so everyone can keep translating for fun.