If, for example, you want to refer to the Db chord in C Phrygian, would you refer to it as the II chord (since it is the 2nd diatonic chord in (C Phrygian) or a flat II chord (since it is flat with respect to the Ionian mode)?

Also, is a triad specifically a grouping of notes consisting of 3 chords each a 3rd apart? Is D sus 4, for instance, a triad? What about E-F-Gb?