Catalysis of the reaction: an N-(1,2 saturated acyl)-(4R)-hydroxysphinganine + 2 Fe(II)- + 2 H+ + O2 = an N-(2R-hydroxyacyl)-4R-hydroxysphinganine + 2 Fe(III)- + H2O.
4-hydroxysphinganine ceramide fatty acyl 2-hydroxylase activity