In 2011 did the Bnei Brak rabbinical court of the late Israeli Haredi Posek rabbi Nissim Karelitz (1926-2019) formally recognize the endogamous Xueta (pronounced “Chueta”) Crypto-Jewish community of the Catalan Island of Majorca in Spain as Halakhically Jewish despite there being aspects of Christianity in their practice of Crypto-Judaism.
This is parallel to the question of the Islamic veneer in some denominations of Median Judaism such as Alevi-Bektashi Judaism and Alawite Judaism. Median Jews are not Muslims, do not practice Islam and have not converted to Islam. Just as the Xuetas are they Halakhically Jewish.