Is it permissible to boycott a sister who follows her Sufi husband, who practices sorcery and charlatanism, and to suffice with greeting her without visiting her home, due to the negative impact on family matters since his arrival?

If what was mentioned about your sister's husband—that he follows the Sufi path and practices charlatanry and sorcery—is true, then he is involved in two reprehensible matters. This is because the prevalent form of Sufism today is largely based on false ideas, and practicing charlatanry and sorcery is a serious matter that can lead to disbelief (kufr). If your sister approves of him in this, then she is his partner in sin. The duty is to advise them both. If they repent, then praise be to Allah. Otherwise, it is permissible to ostracize them in a way that serves a beneficial purpose.