我认为你的译文基本正确.如果结构上稍作调整会更流畅:
There were still sporatic cases of resistance by some secret societies like Heaven-And-Earth Society even 50 years after the Manchu army entered the Shanhaiguan Pass.
之所以说需要调整一下是因为你的开头是根据汉语产生的,但英文是不对的.sporadically一般只能用于否定情况,所以也不太合适,考虑到你已经用了所以就没有改动.供你参考.