“在那件事上，我不会让步”能否翻译为I will not make a concession in that thing.

我觉得后面应该用on that matter，前面的OK了。
或者i won't give in over that case.

Don't expect my concession on that！

可是可以，但很Chinglish.

你可以这样说，I won't give in at that point.

on that thing